TRANSFORMING PHARMACEUTICAL SYNTHESIS WITH SEIN-E-B NANOCOMPOSITE PHOTOCATALYSTS THROUGH 1,4-NAD(P)H COFACTOR REGENERATION AND C-N BOND ACTIVATION

Abstract

The need for sunlight chemical renewal and contemporary organic transformation has fostered the advancement of environmentally friendly photocatalytic techniques. For the first time, we report on the novel crafting of a bright future with selenium-infused Eosin-B (Sein-E-B) nanocomposite photocatalysts in this work. The Sein-E-B nanocomposite materials were created using a hydrothermal process for solar chemical regeneration and organic transformation under visible light. The synthesized samples were subjected to UV-DRS-visible spectroscopy, FT-IR, SEM, EDX, EIS and XRD analysis. The energy band gap of the Sein-E-B nanocomposite photocatalyst was measured using UV-DRS, and the result was around 2.06 eV. to investigate the generated Sein-E-B catalytic activity as a nanocomposite for 1,4-NADH/NADPH re-formation and C-N bond activation. This novel photocatalyst offers a promising alternative for the regeneration of solar chemicals and C–N bond creation between pyrrole and aryl halides.

Specification

DESC:FIELD OF THE INVENTION
The present invention relates to a transforming pharmaceutical synthesis with Sein-E-B nanocomposite photocatalysts through 1,4-NAD(P)H cofactor regeneration and C-N bond activation.
BACKGROUND OF THE INVENTION
References which are cited in the present disclosure are not necessarily prior art and therefore their citation does not constitute an admission that such references are prior art in any jurisdiction. All publications, patents and patent applications herein are incorporated by reference to the same extent as if each individual or patent application was specifically and individually indicated to be incorporated by reference.
Due to several appealing characteristics, such as its low toxicity, low cost, excellent thermal stability, and broad applicability, Eosin-B (E-B) is a widely used photocatalyst for air and water remediation. E-B is employed as a photocatalyst for solar chemical synthesis, C-H, C-N bond activation, etc. when exposed to UV-visible light.[1-7] Nevertheless, the quantum yield of pure E-B is low in producing the C-H and C-N species that convert substrates. Furthermore, E-B's natural structural variability gave them an excellent and adaptable substrate for designing flexible and structurally adjustable heterogeneous photocatalysts with porous architectures and well-defined, separated, and consistent catalytic centers.[8] By altering how the organic linkers and secondary building units co-ordinates, a diverse array of framework structures with different topologies have been achieved.[9] These structure offer a superior channel microenvironment that enhances the proximity of substrates to the photoactive sites, thereby restoring outstanding catalytic capacity and promoting reaction reactivity and selectivity beyond what is observed in reported reactions.[10-11] To enhance E-B photocatalysts, researchers have employed a number of strategies. Using metal doping or coupling to alter E-B has been one approach.[12] Although it was discovered that metal doping increased photocatalytic activity into the visible range, the metal frequently served as a recombination centre, which decreased photonic efficiency.
The enhancement of E-B's photocatalytic performance through elemental doping, such as TiO2 and S, through band gap engineering, has been extensively studied and found to be an effective method.[13-16] Nevertheless, doping carbon nitride, a material with a broader band gap, with selenium (Se), a thin band gap semiconducting element,[17-18] has not been investigated up to this point.[19-21] An intriguing development in carbon nitride-based photocatalytic materials with significantly improved visible light absorption and charge transfer potential could result from such a combination, which has implications for the environment as well as technology. In addition, because of its well-known redox reactivity, selenium may easily supply centres for entrapping photoexcited electrons. [22-24] Reduced interlayer contacts and a smaller radius than that of E-B are other benefits of attaching selenium (1.17 ?) as a light-harvesting material to E-B. This can therefore result in more photocatalytic sites being available, which would enhance photocatalytic activity.
Our hypothesis was that the eosin-B nanocomposite (Sein-E-B) photocatalyst infused with selenium would exhibit significantly enhanced charge transfer, separation, and mobility in addition to producing a greater number of active photocatalytic sites and longer absorption of visible light. We discovered that there is still a dearth of this kind of significant research after reviewing the literature. This is primarily due to the lack of conveniently accessible and appropriate precursors for the production of in situ Sein-E-B that is comparable to commonly available organic precursors for S-doped light harvesting materials.[25-27] Consequently, in order to create a Sein-E-B nanocomposite photocatalyst and gain valuable understanding regarding the influence of Se doping on the band gap, charge transfer mobility, and photocatalytic activity of E-B, a novel synthesis technique utilizing readily available chemicals is imperative. We provide for the first time an accessible synthetic technique for obtaining unique Sein-E-B nanocomposite photocatalysts. The as-synthesized Sein-E-B nanocomposite photocatalyst showed excellent visible light activity for 1,4-NADH/NADPH re-formation and C-N bond activation (Scheme 1), as well as high dependability.
Several patents issued for photocatalysts but none of these are related to the present invention. Patent CN102921416B relates to a silver doped grapheme-zinc oxide nano composite photocatalytic material and a method for preparing the same and belongs to the technical field of nano composite materials and photocatalysis. Graphite oxide is subjected to ultrasonic dispersion to obtain a dispersion solution of graphene oxide; precursors of silver ions and zinc ions are added in the dispersion solution of the graphene oxide, and the mixture is placed into a reaction kettle to be subjected to hydro-thermal treatment to be prepared into the silver doped grapheme-zinc oxide nano composite photocatalytic material in situ after the pH is regulated to an alkaline condition. Photocatalytic degradation experiments show that the silver doped grapheme-zinc oxide nano composite photocatalytic material prepared through the method has good adsorption and visible light photocatalytic degradation effects on rhodamine B and is an ideal nano composite photocatalytic material.
Another patent US7541509B2 discloses a photocatalyst nanocomposite which can be used to destroying biological agents includes a carbon nanotube core, and a photocatalyst coating layer covalently or ionically bound to a surface of the nanotube core. The coating layer has a nanoscale thickness. A method of forming photocatalytic nanocomposites includes the steps of providing a plurality of dispersed carbon nanotubes, chemically oxidizing the nanotubes under conditions to produce surface functionalized nanotubes to provide C and O including groups thereon which form ionic or covalent bonds to metal oxides, and processing a metal oxide photocatalyst sol-gel precursor in the presence of the nanotubes, wherein a nanoscale metal oxide photocatalyst layer becomes covalently or ionically bound to the nanotubes.
Another patent CN107349937B discloses a preparation method of a graphene-based bimetallic sulfide nano composite photocatalyst, which is characterized in that a series of graphene-based bimetallic sulfide composite photocatalysts are synthesized by a simple and mild one-step hydrothermal method, and the morphology size and the oriented growth on the surface of graphene of bimetallic sulfide are regulated and controlled by controlling the hydrothermal reaction temperature, the reaction time, the addition amount of graphene and the content of a metal salt compound in a composite system; in addition, the preparation method provided by the invention is simple in process operation, low in raw material price and suitable for large-scale industrial production.
Another patent US10987659B1 describes a method of synthesizing TiO2/Co3O4 core-shell photocatalysts is provided. The method includes preparing SiO2 hollow nanospheres via sol-gel synthesis in the presence of a triblock copolymer surfactant and a cationic surfactant; adding titanium sec-butoxide to a solution containing the SiO2 hollow nanospheres to provide a first combined sample; calcinating the first combined sample to provide hollow mesoporous TiO2 nanospheres; adding cobalt nitrate to a solution comprising the hollow mesoporous TiO2 nanospheres to provide a second combined sample; and calcinating the second combined sample to provide TiO2/Co3O4 core-shell photocatalysts. Methods of producing hydrogen by water-splitting using TiO2/Co3O4 core-shell photocatalysts are also provided. Such methods include photodepositing platinum onto the photocatalysts during the reaction.
Another patent US20220395821A1 describes a covalent organic framework. The covalent organic frameworks have unique structural and physical properties, which lends them to be versatile in a number of different applications and uses. In one aspect, the covalent organic frameworks are composed of a plurality of fused aromatic groups and electron-deficient chromophores. The covalent organic frameworks are useful as photocatalysts in a number of different applications.
OBJECTS OF THE INVENTION
Main object of the present invention is transforming pharmaceutical synthesis with Sein-E-B nanocomposite photocatalysts through 1,4-NAD(P)H cofactor regeneration and C-N bond activation.
Another object of the present invention is to develop a novel Sein-E-B nanocomposite photocatalyst that enhances the synthesis of pharmaceuticals, focusing on green, sustainable, and economically feasible processes.
Another object of the present invention is to achieve efficient regeneration of the 1,4-NAD(P)H cofactor under photocatalytic conditions, reducing the need for costly, labor-intensive processes typically required for cofactor recycling in pharmaceutical reactions.
Another object of the present invention is to introduce a catalytic system that selectively activates C-N bonds, a critical step in many drug synthesis pathways, allowing for higher specificity and fewer by-products.
SUMMARY OF THE INVENTION
This summary is provided to introduce a selection of concepts, in a simplified format, that are further described in the detailed description of the invention.
This summary is neither intended to identify key or essential inventive concepts of the invention and nor is it intended for determining the scope of the invention.
To further clarify advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings.
Synthesis of selenium-infused Eosin-B ((Sein-E-B) nanocomposite photocatalysts by in situ thermal copolymerization technique shown in scheme 2. By using the mortar and pestle method, 1.0 g of Eosin-B and 3.0 g of selenium powder (Se) were evenly combined. The resulting mixture was then collected in the crucible. The crucible was kept in a muffle furnace and heated to 160 °C for three hours (ramping rate: 5 °C min-1). Following its cooling, the crucible was taken out of the same. Subsequently, a 1.95g product with a pinkish-grey color was produced and purified using acetone and water.
Herein enclosed a Sein-E-B nanocomposite photocatalysts comprising of:
Eosin-B, black selenium powder, pyrrole, 4-chlorobenzaldehyde, 4-bromobenzaldehyde, ethanol (EtOH), acetone, Chloroform (CHCl3), ascorbic acid, NAD+, NADP+ Pentamethylcyclopentadienyl rhodium (III) dichloride dimer, 2, 2'bipyridy dimethylformamide (DMF), Chloroform (CHCl3), silica gel, hexane, ethyl acetate.
A method for preparing the photocatalyst as claimed in claim 1, wherein the photocatalyst is comprising the steps of:
Mixing 1.0 g of Eosin-B and 3.0 g of selenium powder (Se) by using the mortar and pestle method;
Collecting the resulting mixture in the crucible;
Keeping the crucible in a muffle furnace and heated to 160 °C for three hours (ramping rate: 5 °C min-1); and
Taking out crucible of the same after cooling, and 1.95g product selenium-infused Eosin-B nanocomposite with a pinkish-grey color was produced and purified using acetone and water.
The nanocomposite exhibits a stable and reusable photocatalytic performance across multiple cycles without significant degradation of activity or selectivity.
A method for photocatalytic C-N bond activation of the photocatalyst comprising:
Mixing aryl halides (1 mmol) and pyrrole (1 mmol) with the Sein-E-B nanocomposite photocatalyst (10 mg) in 2 mL of ethanol;
Stirring the reaction mixture at room temperature under solar spectrum for 18-30 hours;
Monitoring reaction completion via thin-layer chromatography (TLC);
Filtering and concentrating the reaction product under reduced pressure; and
Purifying the product through silica gel column chromatography using a hexane/ethyl acetate (10:1) eluent to obtain a C-N bond coupling product.
The process for synthesizing 4-(1H-pyrrole-1-yl) benzaldehyde derivatives yielding high-purity C-N bond coupling products suitable for pharmaceutical applications.
BRIEF DESCRIPTION OF THE DRAWINGS
The illustrated embodiments of the subject matter will be understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and methods that are consistent with the subject matter as claimed herein, wherein:
Figure 1. Synthesis of Sein-E-B nanocomposite photocatalysts in situ thermal copolymerization method.
Figure 2. Mechanistic diagram of a) Z-scheme of the natural photosynthetic mechanism b) artificial photosynthetic system simulating the natural photosynthetic system for generation and regeneration of C-N bond activation from aryl halides, pyrrol, and NAD+/NADP+ by newly developed Sein-E-B nanocomposite photocatalyst under solar radiation.
Figure 3. (a) DRS-visible absorption spectra of Sein-E-B nanocomposites photocatalyst along with the tau plot utilised for determining energy band gap (2.06 eV), and (b) UV-visible absorption spectra of E-B photocatalyst.
Figure 4. (a) FTIR spectra of Se (black), E-B (red) monomers and Se-EB (blue) photocatalyst, (b) XRD pattern of E-B (black) and Se-EB photocatalyst (red), (c) Cyclic voltammograms of Sein-E-B nanocomposites photocatalyst, and (d) Cyclic voltammograms of E-B (black) and mixture of Sein-E-B + Rh complex + NAD+ (red) for mechanistic studies. The potential was scanned at 100 millivolts per second employing glassy carbon as working electrode, Hg/HgCl2 served as a reference electrode while platinum was used as a counter electrode in neutral sodium phosphate buffer (100 mM).
Figure 5. E-B and Sein-E-B nanocomposites photocatalytic activity for (a/b) NADH/NADPH regeneration [0.5 mg of photocatalyst, 3.1 mL of sodium phosphate buffer (100 mM, pH 7.0), b-NAD+ (1.24 mmol), Rh (0.62 mmol), and ascorbic acid (1.24 mmol)].
Figure 6. The Nyquist plot of E-B and Sein-E-B nanocomposite photocatalyst was measured in the 0.05M H2SO4 electrolyte.
Figure 7. (a) SEM image of Sein-E-B nanocomposites photocatalysts along with elemental mapping images of (b) carbon (c) Sodium (d) Nitrogen (e) Oxygen (f) selenium, and (g) SEM image of E-B along with elemental mapping images of (h) carbon (i) Oxygen (j) Sodium (k) Nitrogen (l) bromine.
Figure 8. Synthesis of 4(1H-pyrrol-1-yl) benzaldehyde in the presence of newly designed Sein-E-B nanocomposites photocatalyst under blue LED Light.
Figure 9. A plausible mechanism of C-N bond formation between pyrrole and electron-withdrawing aryl halide.
BRIEF DESCRIPTION OF THE DRAWINGS
Table 1. Optimization of the C-N coupling reaction conditions. The C-N coupling reaction via newly designed Sein-E-B nanocomposites photocatalyst under blue LED Light.
DETAILED DESCRIPTION OF THE INVENTION
The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosure as defined by the appended claims.
It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms "a"," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes" and/or "including," when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
In addition, the descriptions of "first", "second", "third", and the like in the present invention are used for the purpose of description only, and are not to be construed as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Thus, features defining "first" and "second" may include at least one of the features, either explicitly or implicitly.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
In some embodiments of the present invention, Synthesis of selenium-infused Eosin-B ((Sein-E-B) nanocomposite photocatalysts by in situ thermal copolymerization technique.
In some embodiments of the present invention, by using the mortar and pestle method, 1.0 g of Eosin-B and 3.0 g of selenium powder (Se) were evenly combined. The resulting mixture was then collected in the crucible.
In some embodiments of the present invention, the crucible was kept in a muffle furnace and heated to 160 °C for three hours (ramping rate: 5 °C min-1). Following its cooling, the crucible was taken out of the same. Subsequently, a 1.95g product with a pinkish-grey color was produced and purified using acetone and water.
In some embodiments of the present invention, the C-N bond coupling product was synthesized by a simple photocatalytic reaction with the help of literature and some minor modifications.
In some embodiments of the present invention, in a dried cylindrical glass tube containing the initial reactant aryl halides (1 mmol), pyrrole (1 mmol), and Sein-E-B nanocomposite photocatalysts (10mg) were mixed in 2 mL ethyl alcohol. After that, the reaction mixture was stirred for 18-30 hours at room temperature under solar spectrum.
In some embodiments of the present invention, subsequently, the usual thin-layer chromatography (TLC) was used to examine the state of reaction completion. After completion of the reaction, the reaction product was filtered, washed with chloroform, and concentrated under reduced pressure.
In some embodiments of the present invention, to extract the appropriate C-N bond coupling product such as 4(1H-pyrrol-1-yl) benzaldehyde derivatives, the final product was purified by silica gel-based column chromatography where hexane/ethyl acetate (10:1) was used as eluent.
Herein enclosed a Sein-E-B nanocomposite photocatalysts comprising of:
Eosin-B, black selenium powder, pyrrole, 4-chlorobenzaldehyde, 4-bromobenzaldehyde, ethanol (EtOH), acetone, Chloroform (CHCl3), ascorbic acid, NAD+, NADP+ Pentamethylcyclopentadienyl rhodium (III) dichloride dimer, 2, 2'bipyridy dimethylformamide (DMF), Chloroform (CHCl3), silica gel, hexane, ethyl acetate.
A method for preparing the photocatalyst as claimed in claim 1, wherein the photocatalyst is comprising the steps of:
Mixing 1.0 g of Eosin-B and 3.0 g of selenium powder (Se) by using the mortar and pestle method;
Collecting the resulting mixture in the crucible;
Keeping the crucible in a muffle furnace and heated to 160 °C for three hours (ramping rate: 5 °C min-1); and
Taking out crucible of the same after cooling, and 1.95g product selenium-infused Eosin-B nanocomposite with a pinkish-grey color was produced and purified using acetone and water.
The nanocomposite exhibits a stable and reusable photocatalytic performance across multiple cycles without significant degradation of activity or selectivity.
A method for photocatalytic C-N bond activation of the photocatalyst comprising:
Mixing aryl halides (1 mmol) and pyrrole (1 mmol) with the Sein-E-B nanocomposite photocatalyst (10 mg) in 2 mL of ethanol;
Stirring the reaction mixture at room temperature under solar spectrum for 18-30 hours;
Monitoring reaction completion via thin-layer chromatography (TLC);
Filtering and concentrating the reaction product under reduced pressure; and
Purifying the product through silica gel column chromatography using a hexane/ethyl acetate (10:1) eluent to obtain a C-N bond coupling product.
The process for synthesizing 4-(1H-pyrrole-1-yl) benzaldehyde derivatives yielding high-purity C-N bond coupling products suitable for pharmaceutical applications.
EXAMPLE 1
EXPERIMENTAL SECTION
Materials and method: Eosin-B, black selenium powder, pyrrole, 4-chlorobenzaldehyde, 4-bromobenzaldehyde, ethanol (EtOH), acetone, Chloroform (CHCl3), ascorbic acid, NAD+, NADP+ Pentamethylcyclopentadienyl rhodium (III) dichloride dimer, 2, 2'bipyridy dimethylformamide (DMF), Chloroform (CHCl3), silica gel, hexane, ethyl acetate was delivered by Sigma-Aldrich. Unless specified otherwise, all of the reagents were utilized without further purification.
Synthesis of selenium-infused Eosin-B (Sein-E-B) nanocomposite photocatalysts: Synthesis of selenium-infused Eosin-B ((Sein-E-B) nanocomposite photocatalysts by in situ thermal copolymerization technique shown in fig 1. By using the mortar and pestle method, 1.0 g of Eosin-B and 3.0 g of selenium powder (Se) were evenly combined. The resulting mixture was then collected in the crucible. The crucible was kept in a muffle furnace and heated to 160 °C for three hours (ramping rate: 5 °C min-1). Following its cooling, the crucible was taken out of the same. Subsequently, a 1.95g product with a pinkish-grey color was produced and purified using acetone and water.
A general technique for photocatalytic C-N bond activation under solar spectrum: The C-N bond coupling product was synthesized by a simple photocatalytic reaction with the help of literature and some minor modifications. [44] In a dried cylindrical glass tube containing the initial reactant aryl halides (1 mmol), pyrrole (1 mmol), and Sein-E-B nanocomposite photocatalysts (10mg) were mixed in 2 mL ethyl alcohol. After that, the reaction mixture was stirred for 18-30 hours at room temperature under solar spectrum. Subsequently, the usual thin-layer chromatography (TLC) was used to examine the state of reaction completion. After completion of the reaction, the reaction product was filtered, washed with chloroform, and concentrated under reduced pressure. To extract the appropriate C-N bond coupling product such as 4(1H-pyrrol-1-yl) benzaldehyde derivatives, the final product was purified by silica gel-based column chromatography where hexane/ethyl acetate (10:1) was used as eluent. [49] 1H-NMR of 4(1H-pyrrole-1-yl) benzaldehyde (CDCl3, 500 MHz) d9.91(s,1H),7.80 (d,2H),7.71(d, 2H),7.27(s,2H), 6.86(s,2H).
Photocatalytic reduction of the NAD+/NADP+ by newly designed Sein-E-B nanocomposite photocatalysts: The photocatalytic reducing of the NAD+/NADP+ from the Sein-E-B photocatalysts swiftly transfers the light generated electrons for NADH/NADPH cofactor regeneration by Rh-complex. Figure 3 shows that in two hours, the coenzyme regeneration of 1,4-NADH/NADPH was 79.23, and /89.46%. NAD+/NADP+ was photo catalytically reduced at room temperature using solar light. The reaction was conducted in a small magnetic stirrer-equipped dried vial tube by combining 3.1mL of neutral sodium phosphate buffer solution (100 mM) with NAD+/NADP+ (1.24 mmol), Rh-complex (0.62 mmol), ascorbic acid (AsA) (1.24 mmol) as a sacrificial agent, and Sein-E-B photocatalyst (0.5 mg). The photocatalytic yields of 1,4-NADH/NADPH cofactor regeneration via Sein-E-B photocatalysts were examined by using the methodology described. [50-51]
EXAMPLE 2
Result and discussion
Technique for mimicking the natural photosynthetic process via newly designed Sein-E-B artificial photosynthetic system: Fig 2 illustrates the Z scheme of the natural photosynthetic system comprising two distinct photosystem (PS) segments, known as PS-700(I) and PS-680(II). The reaction center for solar light absorption is PS-680(II), which contains chlorophyll. Photo-excited electrons are created in the PS-680(II) by absorbing sun light, and these electrons are passed on to the plastocyanin (PC) complex by electron-mediators such as cytochrome complex. The PC complex lowers the photo-oxidized PS-700(I), allowing the photo-excited electron to be transferred into NADPH by ferredoxin NADP+ oxidoreductase (FNR). Therefore, under solar light, natural photosystems PS-700(I) and PS-680(II) are crucial for the synthesis of vital NADH/NADPH coenzymes. [28-32] Our extremely effective Sein-E-B artificial photosynthetic is designed to mimic natural photosynthesis and is intended for both C-N bond activation and NADH/NADPH regeneration. Mimicking natural photosynthesis, we device extremely effective Sein-E-B artificial photosynthetic system intended for both C-N bond activation and NADH/NADPH regeneration. Fig 2 illustrates the reaction mechanism of photocatalytic re-generation of NADH/NADPH cofactor under the influence of solar light. According to scheme 1a, the electron transfer pathways between PS-700(I) and PS-680(II) found in natural photosynthesis is very similar to those between Sein-E-B photocatalysts and Rh-complex [28-32] in Scheme1b. Sein-E-B nanocomposite photocatalyst, a potent light capturing bridge system, collects solar radiation and produces photo-energized electrons, which are then transferred to the NAD+. It absorbs electrons and reduces readily. Rh-complex received proton from buffer aqueous medium and electrons transfer to oxidized form NAD+/NADP+, reduced into 1,4 NADH/NADPH fine chemicals. In this process, Rh-complex acting as a mediator for the transfer of protons and electrons between NAD+/NADP+ and Sein-E-B nanocomposite photocatalysts. However, the newly developed Sein-E-B nanocomposite photocatalysts also has the ability to C-N coupling formation under solar radiation.
Diffuse reflectance UV-visible spectroscopy, FTIR spectroscopy, X-ray diffraction analysis (XRD) and cyclic voltammograms studies:
The UV-visible spectra of the nanocomposite photocatalysts Se,[33] Eosin-B, and Sein-E-B are displayed in Figure 3. A very weak band in the 200-400 nm range was seen on the Se. Conversely, at the same concentration, the Q-bands of Sein-E-B and Eosin-B (530 nm) had a higher absorbance and were wider. Strong intermolecular interactions are suggested to be present in Sein-E-B and E-B by the broadening of the Q-band and red shift in absorbance maxima in E-B/Sein-E-B relative to Se.
Further support for the infusion of Se with E-B was given by FTIR research. Se's spectra (Figure 2a) did not show any distinctive absorption bands.[34] Furthermore, E-B showed distinctive bands at 2915, 1442, 1676, and 1088 cm-1, which are corresponds to the C-H, C=O, C-O-C, and C-H bonds.[35] Infusing of E-B to Se was confirmed by the lack of a peak at 650 cm-1 in the spectrum of Sein-E-B (Fig. 4a) and the simultaneous formation of additional bands at 762 cm-1 assigned to the C-Se bending of the amide group.[36] Furthermore, distinct functional groups in molecules can be recognized via vibrational spectroscopy, such as infrared spectroscopy, by their distinctive vibrational frequencies. In the spectrum of Sein-E-B, there is no longer a peak at 650 cm-1, indicating that the characteristic vibration associated with that frequency is absent. This supports the notion that Se has been successfully infused or reacted with E-B. Further evidence of alterations in the molecular structure, particularly involving the interaction of carbon (C) and selenium (Se) in the amide group, is shown by the development of additional bands at 762 cm-1, which corresponds to the C-Se bending of the amide group. The characterization of the chemical changes that take place during the infusion process is aided by this knowledge. As a result, hydrothermal treatment is useful for grafting a stable E-B sensitization layer onto sulfur nanoparticle surfaces. This would improve and stabilize the photocatalysts' ability to regenerate 1,4-NADH/NADPH and promote C-N bond activation.
The Sein-E-B photocatalyst intense spectrum range (Figure 4b) illustrates the material's structural characteristics. Figure 2b shows the XRD patterns of the E-B and Sein-E-B nanocomposites photocatalysts, respectively. The XRD of E-B and Sein-E-B nanocomposites photocatalysts showed the two most intense peaks of crystalline 23.5° and 29.7°, which were assigned to the crystal planes of (100) and (101), [37] which conform to the infusion of Se to E-B. Furthermore, distinct crystallographic planes inside a crystalline material correspond to peaks at particular angles in X-ray diffraction. The fact that the infusion of Se is responsible for these peaks implies that the presence of sulfur has affected the crystal lattice's atom arrangement, resulting in the XRD pattern's observed modifications.
Proof of 1,4-NADH/NADPH re-generation through cyclic voltammetry (CV): Cyclic voltammetry (CV) can help us understand how the process works. Consequently, we investigated the electrochemical characteristics of Sein-E-B nanocomposites photocatalyst and Rh using CV on glassy carbon (working) chloride(reference), mercury-mercury (I) and platinum (as counter) electrodes at pH 7.0 in a phosphate buffer (100 mM). Rh and Sein-E-B nanocomposites photocatalysts had reduction potentials of approximately -0.71 V and -1.25 V (Figure 4c), respectively. When Rh and Sein-E-B nanocomposites photocatalyst both were present in the solution at the same time, the CV voltammogram changed. This can be due to interactions between Rh and Sein-E-B nanocomposites photocatalyst. [27,38] It may also be regarded as an anodic change in Sein-E-B nanocomposites photocatalyst decrease. As per reported literature,[38] the Sein-E-B-Rh complex also demonstrated a notable rise in the reduction peak current with NAD+, indicating that the Sein-E-B-Rh system (Figure 4d) could catalyze the reduction of NAD+ .[38] It has been previously observed that the catalytic impact of Rh results in a significantly higher rate of Rh reduction in the presence of NAD+ [39-40] The lack of an oxidation peak indicated that the electrochemistry of the Sein-E-B-Rh complex adhered to Rh behavior (involving a two-electron reduction followed by chemical protonation).The photoelectrical behavior of Sein-E-B could be the reason for the catalytic activity of the Sein-E-B-Rh complex because the excited electron of Sein-E-B is easily transferred to Rh. As per researchers,[41] the photoelectrical property of a hybrid light-harvesting molecule is caused when the electrons transition from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO), which is then transferred into the rhodium complex. In this scenario, the photoexcitation of the Sein-E-B electron from HOMO (E = -5.5 eV) to LUMO (E = -3.25 eV) causes it to cascade into Rh (E = -3.96 eV) without radiation. The proximity and potential gradient existing between the light-harvesting Sein-E-B photocatalyst and the electrocatalytic Rh center enables efficient electron transport from the former to the latter. In aqueous environment the resulting electrically reduced Rh, [Cp*Rh(bpy)], is chemically protonated and subsequently engages in a catalytic reaction with NAD+/NADP+ that regenerates 1,4-NADH/NADPH (79.23/89.46%) higher than E-B photocatalyst (Figure 5).
Additionally, the newly developed Sein-E-B nanocomposite photocatalyst has efficient solar light harvesting capability and slow recombination charges making it overall better than the E-B photocatalyst (Figure 6). As a result, the newly developed photocatalyst offers important additional applications for organic transformation or the C-N bond coupling reaction.
Electrochemical impedance spectroscopy study of E-B and Sein-E-B nanocomposite photocatalyst: On the other hand, the inclusion of selenium on the Sein-E-B nanocomposite photocatalyst decreases space charge capacitance and resistance of charge transfer, as illustrated by the shorter semicircle produced in the higher frequency range in the Nyquist diagram (Figure 6) These findings suggest that electrons in the bare E-B photocatalyst take more time reaching the semiconductor/electrolyte interface, where photocatalytic degradation occurs, and that more number of electrons may recombine with the holes before interacting with pollutants.
The remarkable photocatalytic activity of the Sein-E-B nanocomposite photocatalyst is attributed to lower rate of e-/h+ recombination because of reduced charge transfer resistance and space charge capacitance which allows effective charge separation of electron/hole pairs and rapid conduction to the surface.
Scanning electron microscopy used to study newly designed Sein-E-B nanocomposites material morphology: Scanning electron microscopy images were used to observed the morphological changes in the material. In the Figure 7, SEM image of E-B shows the agglomerated soft like material. Whereas in Sein-E-B nanocomposite, Selenium infuses the E-B and change the morphology of the E-B into popcorn-like shapes. Hence, this results clearly indicate the infusion of E-B by Selenium and formation of Sein-E-B nanocomposite photocatalyst. To further understand the composition of each element in the E-B and Sein-E-B nanocomposites photocatalyst, the elemental mapping was used shown in Figure 7(b-f). All element constituents of E-B appeared in elemental mapping spectra including carbon, oxygen, and bromine while Sein-E-B photocatalyst appeared in the elemental mapping including carbon, oxygen, and selenium. Here, a difference in the particle is observed, selenium (Figure 7f) is detected with good carbon (Figure 7b) distribution in the whole area of newly synthesized polymeric Sein-E-B nanocomposites photocatalyst. This implies that the Sein-E-B nanocomposite's photocatalyst capacity to effectively catalyze photochemical reactions, it is a desired quality in various applications, such as energy conversion or environmental cleanup, is related to the distinctive shape shown in Figure 7. On the other hand, selenium element presents in newly designed Sein-E-B nanocomposite's photocatalyst and absent in E-B (Figure 7g-i), which is also proved the infusion of Se with E-B.
Table 1. Optimization of the C-N coupling reaction conditions. The C-N coupling reaction via newly designed Sein-E-B nanocomposites photocatalyst under blue LED Light.
Entry Reagent ratio (a:b) Photocatalyst Time (h) Yield (%)
1
2
3
4
5
6
7
8
9
10
11
12 1:1
1:1
1:1
1:1
1:1
1:1
1:0.9
1:1
1:1.1
1:1.12
1:1
1:1 5
10
15
20
25
15
15
15
15
15
-
No. light 24
24
24
24
24
05
18
18
15
18
18
18 45
69
90
94
94
25
82
90
94
94
Trace
Trace


Optimized Reaction conditions: Pyrrole (0.87 g, 10 mmol), Chloro/bromobenzaldehyde (1.25 g, 10 mmol), Sein-E-B nanocomposite photocatalyst (15 mg), and Blue LED. The reaction between pyrrole and chloro/bromobenzaldehyde was investigated using the synthesized and characterized Sein-E-B nanocomposite photocatalyst (fig 8). 0.87 g (10 mmol) of pyrrol and 1.27 g (10 mmol) of chloro/bromobenzaldehyde were placed in a 10-mL cylindrical container and charged with photocatalyst in a homemade photocatalytic reactor that was exposed to a 5 W LED light source. Following a predetermined amount of time, the reaction was extracted using brine solution and ethyl acetate, an organic solvent, by exploiting the salt ion effect. To obtain the required product, the organic layer was recovered and vacuum-evaporated. [42-44] It was possible to optimize the C-N coupling reaction with regard to a variety of factors, including the impact of catalyst loading, duration, light intensity, and molar ratio. By varying the catalyst amount from 5 to 25 mg, the impact of catalyst loading was investigated. Following the addition of 20 and 25 mg of photocatalyst, there is no further change in yield (Entry 4 to 5, Table 1), but as the catalyst is loaded up to 15mg, the product yield rose to 90% Furthermore, by altering the reaction time, the effect of duration on the photocatalytic reaction was investigated. The reaction's length was varied from five to twenty-four hours while the catalyst loading was optimized. There is no additional rise in yield at 24 hours (Entry 5, 9, and 10 Table 1), while a gradual rise in yield has been observed with the rise in time up to 18 hours with 90% yield of product. Additionally, an investigation was conducted into the impact of molar ratio on the photocatalytic reaction at the optimal loading and duration of the catalyst. We have investigated how changing the molar ratio of chloro/bromobenzaldehyde while maintaining a constant pyrrol ratio has affected the rate of product production. The optimal yield (Entry 8, Table 1) was afforded by varying the pyrrole and chloro/bromobenzaldehyde ratio from 1:0.9 to 1:1.2 (Entry 7 to 10, Table 1). Additionally, same response was tested with 7 W and 17 W LED lights (Entry 9 and 10, Table 1), with 5 W LED light producing the best results. Additionally, a controlled reaction was conducted in the dark and without a photocatalyst; this reaction produced no products, as shown in entries 11 and 12 in Table 1. Therefore, 15 mg was effective with 18 hours under 5 W LED light in a DIY photoreactor, and these are the ideal conditions for C-N coupling employing Sein-E-B nanocomposite photocatalysts. The coupling reaction between pyrrole and chloro/bromobenzaldehyde (fig 8) was first examined and then substrates with electron-withdrawing (fig 8) substituents were considered. The findings demonstrated that, in the optimal conditions, the withdrawing substituents on the aryl halide were more favorable for the C-N coupling reaction. [45]
Plausible Mechanism of C-N Bond Activation: Unveiling the Power of Sein-E-B Nanocomposite Photocatalysts in Pyrrole and Electron-Withdrawing Aryl Halide Coupling under Blue LED Illumination:
To initiate the photocatalytic reaction of pyrrole with an electron-drawing aryl halide, blue LED light is irradiated on the Sein-E-B photocatalyst, resulting in excitons (holes (h+) and electrons (e-) [46] The electrons generated by light attack the aryl halide, producing the radical anion referred to as intermediate I, and then it undergoes a homolytic fission leading to formation of phenyl radical, referred to as intermediate II along with the removal of the halide anion. This intermediate II phenyl radical was trapped by TEMPO and formed a TEMPO adduct, which was validated using the disclosed approach. [46-48] Furthermore, holes oxidise the pyrrole, removing electrons from it and regenerating the photocatalyst. A radical cation of pyrrole intermediate III was produced. [46-48] Furthermore, homolytic fission occurs when the H+ ion is lost, resulting in the generation of an intermediate IV.[48] Finally, the interaction between phenyl radical intermediate II and intermediate IV occurs, resulting in the formation of product V.
Conclusions
In conclusion, we have created a novel Sein-E-B photosynthetic system that accurately simulates natural photosynthesis. With a catalytic efficiency of 79.23/89.46%, this photocatalytic system reveals an effective method for the regeneration of 1,4-NADH/NADPH and also illustrates how to activate C-N bonds when exposed to solar light. Under ambient conditions, the reduction of NAD(P)+ to NAD(P)H is carried out through the through-space transfer of multielectron by the newly designed light-harvesting Sein-E-B photocatalyst in conjunction with the electron mediator of Rh complex. Based on the findings, the Sein-E-B photocatalyst shows great potential as a platform for photochemistry and medicinal chemistry.
Non Patent References
[1] M. Chakraborty, A. K. Panda, Acta, Part A, 2011, 81, 458-465.
[2] S. J. He, X. Y. Du, Q. Wang and J. Xu, Adv. Mater. Res., 2013, 827, 3-7.
[3] H. Rahman, Int. J. Pharm. Pharm. Sci., 2017, 9, 1
[4] P. Singh, S. Chaubey, C. Singh, S. Singh, R.K. Yadav, A. P. Singh, P.D. Subhash, D. Tiwari, React. Chem. Eng., 2023, 8, 1072-1082.
[5] H. K. Singh, A. Kamal, S. Kumari, D. Kumar, S. K. Maury, V. Srivastava, S. Singh, ACS Omega, 2020, 5, 46, 29854-29863.
[6] S Soni, P. Pali, M. A. Ansari, M. S. Singh, J. Org. Chem. 2020, 85, 15, 10098-10109.
[7] S. Rossi, F. Herbrik, S. Resta, A. Puglisi, Molecules, 2022, 27, 5096.
[8] P. Fita, M. Fedoseeva, E. Vauthey, J. Phys. Chem. A 2011, 115, 12, 2465-2470.
[9] V. Pascanu, G. G. Miera, A. K. Inge, B. M. Matute J. Am. Chem. Soc. 2019, 141, 18, 7223-7234.
[10] S. Jana, M. Uchman, Progress in Polymer Science, 2020, 106, 101252.
[11] J. B. Fankam, G. W. Ejuh, F. T. Nya, J. M. B. Ndjaka, Optical and Quantum Electronics, 2020, 52, 292.
[12] J. A. Khan, M. Sayed, N. S. Shah, S. Khan, Y. Zhang, G. Boczkaj, H. M. Khan, D. D. Dionysiou, Applied Catalysis B: Environmental, 2020, 265, 118557.
[13] S. C. Yan, Z. S. Li, Z. G. Zou, Langmuir, 2010, 26, 3894-3901.
[14] J. Li, B. Shen, Z. Hong, B. Lin, B. Gao, Y. A. Chen, Chem. Commun. 2012, 48, 12017-12019.
[15] G. Dong, K. Zhao, L. Zhang, Chem. Commun. 2012, 48, 6178-6180.
[16] Z. Lin, X. Wang, Angew. Chem. Int. Ed. 2013, 52, 1735-1738.
[17] J. A. Johnson, M.-L. Saboungi, P. Thiyagarajan, R. Csencsits, D. Meisel, J. Phys. Chem. B, 1999, 103, 59-63.
[18] M. P. Kalamuei, M. M. Kamazani, M. S. Niasari, S. H. Mashkani, Ultrason. Sonochem, 2015, 23, 246-256.
[19] S. Cao, J. J. Yu, Phys. Chem. Lett. 2014, 5, 2101-2107.
[20] S. Cao, J. Low, J. Yu, M. Jaroniec, Adv. Mater. 2015, 27, 2150-2176.
[21] J. Wen, J. Xie, X. Chen, X. Li, Appl. Surf. Sci. 2017, 391, 72-123
[22] E. Y. Tsui, K. H. Hartstein, D. R. Gamelin, J. Am. Chem. Soc. 2016, 138, 11105-11108.
[23] H. J. Reich, R. Hondal, J. ACS Chem. Biol. 2016, 11, 821-841.
[24] E. M. Rockafellow, J. M. Haywood, T. Witte, R. S. Houk, W.S. Jenks, Langmuir, 2010, 26, 19052-19059.
[25] S. Singh, R. K. Yadav, T. W. Kim, C. Singh, P. Singh, S. Chaubey, A. P. Singh, J.-O. Baeg, S. K. Gupta, D. Tiwary, ACS.Energy Fuels, 2022, 36, 15, 8402-8412.
[26] M. Zhu, C. Zhai, L. Qiu, C. Lu, A. S. Paton, Y Du, M. C. Goh, ACS Sustainable Chem. Eng. 2015, 3, 12, 3123-3129.
[27] A. Kumar, R. K. Yadav, N.-J. Park, J.-O. Baeg, ACS Appl. Nano Mater. 2018, 1, 1, 47-54.
[28] E. J. Bastian, R. B. Martin, J. Phys. Chem. 1973, 77, 1129-1133.
[29] H. Q. Jiang, H. Endo, H. Natori, M. Nagai, K. Kobayashi, J. Eur. Ceram. Soc. 2008, 28, 2955-2962.
[30] C. A. Wang, Z. K. Zhang, T. Yue, Y. L. Sun, L. Wang, W. D. Wang, Y. Zhang, C. Liu, W. Wang, Chem. - A Eur. J. 2012, 18, 6718-6723.
[31] C. A. Wang, Y. F. Han, Y. W. Li, K. Nie, X. L. Cheng, J. P. Zhang, RSC Adv. 2016, 6, 34866-34871.
[32] C. A. Wang, Y. W. Li, X. M. Hou, Y. F. Han, K. Nie, J. P. Zhang, Chemistry Select, 2016, 1, 1371-1376.
[33] S. G. Bolton, M. D. Pluth, Chem. Sci., 2020, 11, 11777-11784.
[34] B. Wang, J. Zhang, Z. Xia, M. Fan, C. Lv, G. Tian, X. Li, Nano Research, 2018,11, 2460-2469.
[35] P. Bhatia, S. Pandey, R. Prakash, T.P. Nagaraja, Journal of Biologically Active Products from Nature, 2014, 4, 354-364.
[36] G Huang, Y Lin, L Zhang, Z Yan, Y Wang, Y Liu, Nature, 2019, 9, 19651.
[37] N. Bisht, P. Phalswal, P. K. Khanna, Mater. Adv., 2022, 3, 1415-1431.
[38] R. K. Yadav, J.-O. Baeg, A. Kumar, K-j. Kong, G. H. Oha, N.-J. Park, J. Mater. Chem. A, 2014, 2, 5068-5076.
[39] Y. Han, G. Wu, H. Li, M. Wang, H. Chen, Nanotechnology, 2010, 21, 185708.
[40] T. Yoshida, K. Terada, D. Schlettwein, T. Oekermann, T. Sugiura and H. Minoura, Adv. Mater., 2000, 12, 1214.
[41] C. B. Park, S. H. Lee, S. Kale, S. M. Lee and J. O. Baeg, Chem. Commun., 2008, 42, 5423-5425.
[42] R. K. Yadav, A. Kumar, N.-J. Park, D. Yadav, J. Y. Kim, J.-O. Baeg, Sustainable Energy Fuels, 2019, 3, 3324-3328.
[43] H. Stambulyana, T. G. Minehan, Org. Biomol. Chem., 2016, 14, 8728-8731
[44] S.H. Barange, P.R. Bhagat ChemistrySelect, 2022, 7, e202201177.
[45] M. S. Oderinde, N. H. Jones, A. Juneau, M. Frenette, B. Aquila, S. Tentarelli, D. W. Robbins, J. W. Johannes Angew. Chem. Int. Ed. 2016, 55, 1 - 6.
[46] S. Uttamrao. Raut, S. Avinash. Deshmukh, S. H. Barange, P. Rambhau. Bhagat Catalysis Today, 2023, 408, 81-91.
[47] A. Wimmer, B. König, Beilstein J. Org. Chem. 2018, 14, 54-83.
[48] M. N. Lavagnino, T. Liang, D. W. C. MacMillan, Proc Natl Acad Sci U S A, 2020, 117 (35), 21058-21064.
[49] J. Barber, B. Andersson, Nature 1994, 370, 31-34.
[50] S. Chaubey, R. K. Yadav, S. K. Tripathi, B. C. Yadav, S. N. Singh, T. W. Kim, Photochem Photobiol., 2022, 98, 150-159.
[51] R. K. Yadav, J. O. Baeg, G. H. Oh, N. J. Park, K. J. Kong, J. Kim, D. W. Hwang and S. K. Biswas, J. Am. Chem. Soc., 2012, 134, 11455-11461. ,CLAIMS:1. A Sein-E-B nanocomposite photocatalysts comprising of:
Eosin-B, black selenium powder, pyrrole, 4-chlorobenzaldehyde, 4-bromobenzaldehyde, ethanol (EtOH), acetone, Chloroform (CHCl3), ascorbic acid, NAD+, NADP+ Pentamethylcyclopentadienyl rhodium (III) dichloride dimer, 2, 2'bipyridy dimethylformamide (DMF), Chloroform (CHCl3), silica gel, hexane, ethyl acetate.
2. A method for preparing the photocatalyst as claimed in claim 1, wherein the photocatalyst is comprising the steps of:
i. Mixing 1.0 g of Eosin-B and 3.0 g of selenium powder (Se) by using the mortar and pestle method;
ii. Collecting the resulting mixture in the crucible;
iii. Keeping the crucible in a muffle furnace and heated to 160 °C for three hours (ramping rate: 5 °C min-1); and
iv. Taking out crucible of the same after cooling, and 1.95g product selenium-infused Eosin-B nanocomposite with a pinkish-grey color was produced and purified using acetone and water.
3. The method as claimed in claim 2, wherein the nanocomposite exhibits a stable and reusable photocatalytic performance across multiple cycles without significant degradation of activity or selectivity.
4. A method for photocatalytic C-N bond activation of the photocatalyst as claimed in claim 2, wherein the method for photocatalytic C-N bond activation of the photocatalyst comprising:
• Mixing aryl halides (1 mmol) and pyrrole (1 mmol) with the Sein-E-B nanocomposite photocatalyst (10 mg) in 2 mL of ethanol;
• Stirring the reaction mixture at room temperature under solar spectrum for 18-30 hours;
• Monitoring reaction completion via thin-layer chromatography (TLC);
• Filtering and concentrating the reaction product under reduced pressure; and
• Purifying the product through silica gel column chromatography using a hexane/ethyl acetate (10:1) eluent to obtain a C-N bond coupling product.
5. The method as claimed in claim 4, wherein a process for synthesizing 4-(1H-pyrrole-1-yl) benzaldehyde derivatives yielding high-purity C-N bond coupling products suitable for pharmaceutical applications.

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