CuNiO₂ nano catalyst for efficient Csp²–S bond formation in water: toward green synthesis of bioactive molecules

Abstract

A green and efficient method for Migita-type Csp²–S cross-coupling of aryl halides with thiols has been developed using a heterogeneous CuNiO₂ bimetallic nanocatalyst. This low-cost, easily synthesized catalyst operates under ligand-free conditions in water, enabling the coupling of heterocyclic thiols such as benzothiazole-2-thiol, benzooxa-zole-2-thiol, 1,3,4-thiadiazole-2-thiol, and thiazole-2-thiol with challenging electrophiles like 3-bromopyridine, 2-bromoquinoline, and 5-bromo-1H-indole. The methodology demonstrates broad scope and practicality, including gram-scale synthesis of diverse aryl, heteroaryl, and alkyl thioethers bearing bioactive motifs. Compared to existing systems, this catalyst exhibits greater sustainability and catalytic performance. Control experiments confirm a synergistic effect between Cu and Ni, while DFT calculations indicate that the reaction preferentially occurs at the Ni center, with an overall Gibbs free energy change of −102.7 kcal mol⁻¹.

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Introduction

In organic synthesis, transition metal catalysts have significantly advanced carbon–heteroatom cross-coupling reactions. Among these, C–S bond formation remains particularly challenging due to the strong coordinating nature of sulfur, which can deactivate metal centers and reduce catalytic efficiency.¹ Despite this, C–S cross-coupling has become a highly attractive strategy, driven by the widespread presence of thioethers, sulfoxides, and sulfones in drug molecules and biologically active compounds.² Thioether derivatives, in particular, are found in approximately 20% of FDA-approved pharmaceuticals.³ Beyond medicinal chemistry, thioethers also play a crucial role in materials science as functional fragments and polymerization precursors in soft materials, in semiconductor fabrication, and across various scientific and industrial applications.^4–6

The first successful C–S cross-coupling reaction was reported by Japanese chemists Kosugi and Migita between 1978 and 1980.^7,8 Since then, this field has witnessed remarkable evolution from the use of homogeneous palladium catalysts^9a to more sustainable and earth-abundant transition metals such as copper,^9b cobalt,^9c iron,^9d and nickel,^9e–j often employed in combination with bulky phosphorus- or nitrogen-based ligands. In the early 21st century, the development of nanoparticle-based and heterogeneous catalysts further advanced the field by offering recyclability, facile catalyst separation, and reduced metal contamination.¹⁰

To minimize bulk chemical waste generated from toxic and flammable organic solvents, water has emerged as an ideal green solvent for organic synthesis due to its abundance, non-toxicity, non-flammability, and simple work-up procedures.¹¹ Consequently, C–S cross-coupling reactions have been extensively explored in aqueous media.¹² Only a few examples of bimetallic systems such as Ni–Zr,^13a Cu–Fe,^13b Pd–Fe,^13c Ni–Fe,^13d and Co–Fe^13e have been reported for C–S cross-coupling in water. However, these studies often lacked detailed mechanistic understanding, exhibited limited substrate scope, and offered minimal synthetic applicability for broader practical use.

Recently, Lipshutz and co-workers demonstrated the use of recyclable water as a reaction medium for C–S cross-coupling (Fig. 1a).¹⁴ Our group has previously developed a CuMoO₄ bimetallic nano catalyst for efficient C–S cross-coupling at room temperature in DMSO, highlighting the concept of bi-metallic synergy where one metal enhances the catalytic activity of the other (Fig. 1b).^15,16

Fig. 1 Representative literature reports on C–S cross-coupling by using metal catalysis (a and b) and this work (c).

However, the poor reactivity of aliphatic and heteroaromatic thiols, the absence of significant synthetic applications toward bioactive molecules, and the lack of mechanistic understanding remain major limitations of the previous report. To overcome these challenges and advance sustainable methods for thioether synthesis, we have developed an oxo-bridged bimetallic CuNiO₂ nano catalyst for C–S cross-coupling reactions in water (Fig. 1c). This methodology enables the direct synthesis of a wide range of bioactive molecules on a gram scale. A broad substrate scope was achieved, encompassing diverse heteroaryl halides and thiols (both alkyl and heteroaryl), affording good to excellent isolated yields. Furthermore, the reaction mechanism was elucidated through density functional theory (DFT) calculations.

Results and discussion

The catalyst was prepared via hydrothermal decomposition of Cu(OAc)₂·H₂O and NiCl₂·6H₂O (both purchased from Sigma-Aldrich) in water at 150 °C using a hydrothermal autoclave (Fig. 2). The resulting CuNiO₂ catalyst was obtained as a smoky black solid and thoroughly characterized by IR, powder XRD, XPS, EDX, and SEM analyses. XPS spectra exhibited characteristic Cu²⁺ peaks at binding energies of 932.78 eV (2p_3/2) and 953.05 eV (2p_1/2), along with Ni²⁺ peaks at 855 eV (2p_3/2) and 873 eV (2p_1/2). The IR band observed at 681 cm⁻¹ indicates the presence of a [Cu–O–Ni] linkage in the catalyst (for details, see SI).^17,18

Fig. 2 Synthesis of CuNiO₂ catalyst.

The reaction optimization was carried out using 4-methoxyiodobenzene and adamantane-1-thiol (AdSH) as model substrates (Table 1). Gratifyingly, the desired thioether 1 [(adamantan-1-yl)(4-methoxyphenyl)sulfane] was obtained in 93% yield when the substrates were stirred with 5 mol% of CuNiO₂, 1 equivalent of tetrabutylammonium bromide (TBAB), and 1.5 equivalents of K₂CO₃ in water at 80 °C (Table 1, entry 8). Among the solvents tested—THF, DMSO, toluene, acetonitrile, ethanol, DMF, and DMA—water proved to be the most efficient medium for this transformation (Table 1, entries 1–7).

Table 1 Effect of catalyst and control experiments

Sl. no.	Catalyst (5 mol%)	Base (1.5 equiv.)	Solvent (1 mL)	Yield^a^,^b (%)
a Reaction condition: 4-iodoanisole (1 mmol), adamantane-1-thiol (1.2 equiv.), base (1.5 equiv.), solvent (1 mL) were stirred at 80 °C for 10 h. b Isolated yield. c <5% disulfide observed. d TBAB (1 equiv.). e TBAF. f PEG. g H2O : DMSO (4 : 1) at 50 °C, AdSH = adamantane-1-thiol.
1	CuNiO2	K2CO3	THF	13
2	CuNiO2	K2CO3	DMSO	21
3	CuNiO2	K2CO3	Toluene	14
4	CuNiO2	K2CO3	CH3CN	32
5	CuNiO2	K2CO3	EtOH	nd
6	CuNiO2	K2CO3	DMF	50
7	CuNiO2	K2CO3	H2O	77^c
8	CuNiO2	K2CO3	H2O	93^d
9	CuNiO2	KOH	H2O	91^d
10	CuNiO2	Na2CO3	H2O	72^d
11	CuNiO2	K2CO3	H2O	79^e
12	CuNiO2	K2CO3	H2O	25^f
13	CuNiO2	K2CO3	H2O : DMSO	25^g
14	Cu(OAc)2·H2O	K2CO3	H2O	62^d
15	NiCl2·6H2O	K2CO3	H2O	10^d
16	NiCl2·6H2O + Cu(OAc)2·H2O	K2CO3	H2O	75^d
17	None	K2CO3	H2O	0^d
18	CuNiO2	—	H2O	0^d

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Among the various bases screened, KOH, NaOH, Cs₂CO₃, KOtBu, KOAc, NaH, K₂CO₃, and Na₂CO₃, K₂CO₃ provided the best result (for details, see SI). Replacing TBAB with TBAF (tetrabutylammonium fluoride) or PEG (polyethylene glycol) resulted in a significant decrease in yield to 79% and 25%, respectively (Table 1, entries 12–13). The optimal reaction temperature was found to be 80 °C, giving the highest yield. Interestingly, even at 50 °C, the reaction afforded 25% of the thioether product 1 when a 4 : 1 mixture of H₂O and DMSO was used as the solvent (for details, see SI).

To gain insight into the catalytic activity, control experiments were performed (Table 1, entries 15–18). A reaction carried out with 5 mol% of Cu(OAc)₂·2H₂O alone afforded 60% of the product, while NiCl₂·5H₂O alone provided only 10%. Interestingly, when a combination of Cu(OAc)₂·2H₂O (5 mol%) and NiCl₂·5H₂O (5 mol%) was used, the yield increased to 75%, indicating a synergistic catalytic effect between copper and nickel in CuNiO₂.¹⁹ It is noteworthy that aliphatic and heterocyclic substrates are compatible in RC-1 condition including gram-scale synthesis of bioactive molecules in water at 80 °C (Schemes 1, 2 and 4–6); whereas aromatic thiols work well in RC-2 conditions in 4 : 1 ratio of water and DMSO at 50 °C (for details see SI). Subsequently, we examined the reactivity of various substrates using the pre-synthesized CuNiO₂ catalyst. It is well known that long-chain thiols often exhibit poor reactivity in such transformations due to their low solubility.¹⁵ Aliphatic thiols are more nucleophilic to form strong metal–sulphur bond in comparison to acidic nature of Aromatic thiols. So, aliphatic thiols can deactivate the catalyst by chelation easily.^14,20b,21

Scheme 1 Substrate scope of alkyl- and benzylic thiols with aryl(hetero) iodides by CuNiO₂ catalyst. ^aCatalyst (5 mol%), aryl iodide (1 mmol), thiol (1.2 equiv.), K₂CO₃ (1.5 equiv.), TBAB (1 equiv.), H₂O (1 mL) were stirred at 80 °C for 10 h, ^bisolated yield, optimized reaction condition 1 (RC-1).

Scheme 2 Synthesis of benzothiazole, thiadiazole, thiazoles thio-derivatives (compatibility of catalyst with heterocyclic derivatives). ^aCatalyst (5 mol%), aryl iodide (1 mmol), thiol (1.2 equiv.), K₂CO₃ (1.5 equiv.), TBAB (1 equiv.) H₂O (1 mL) was stirred at 80 °C for 10 h, ^bisolated yield, optimized reaction condition 1 (RC-1).

Moreover, alkyl thiols have traditionally posed challenges in cross-coupling reactions because of their high nucleophilicity that can form a metal–ligand complex and deactivate the catalyst.²¹ Interestingly, our reaction was not affected by metal–ligand chelation for aliphatic thioethers even if in water solvent (Scheme 1).

Dodecyl and octyl thiols reacted efficiently with 3-bromopyridine, 5-bromo-1H-indole, and substituted iodo-benzenes bearing 4-OMe and 4-CHO groups, affording the corresponding thioethers (2–6) in high yields without any chelation or solubility issues. Notably, reactions of dodecylthiol with 3-bromopyridine and 5-iodoindole furnished the desired products in 88% (2) and 95% (3) yields, respectively, demonstrating the absence of catalyst chelation. Similarly, the cyclohexylthiol underwent smooth coupling with 4-acetyliodobenzene to afford the thioether 1-(4-(cyclohexylthio)phenyl)ethan-1-one (7) in 85% yield. Furthermore, the sterically demanding and less reactive ter-tiary alkyl 1-adamantanethiols successfully delivered the corresponding thioethers (1, 8–10) in excellent yields ranging from 87% to 93%.

The structure of ((1S,3S)-adamantan-1-yl)(4-nitrophenyl)sulfane (9) was confirmed by single-crystal X-ray analysis (CCDC no. 2388312). 2-Mercaptoethan-1-ol derivatives 11 and 12 were synthesized in 55–95% yields from 2-bromoquinoline and 4-methoxyiodobenzene, respectively. Benzyl thioethers 13–14 were obtained in 88–92% yields using a carbonate base in water. Remarkably, heterocyclic furan-2-ylmethane thiols coupled efficiently with aryl iodides bearing various functional groups (CHO, CN, OAc, OMe) to afford the corresponding thioethers 15–19 in 70–92% yields, without metal chelation by oxygen, nitrogen, or sulfur.

Heterocyclic thiols containing N, S, and O-atoms are prone to coordination, which can deactivate catalysts during coupling reactions. Previous studies have shown that nickel catalysts lose activity due to chelation with heteroatoms in the reaction medium.^21c We explored the reactivity of heterocyclic thiazoles using our CuNiO₂ catalyst with both electron-donating and electron-withdrawing aryl iodides (Scheme 2). Benzothiazole-2-thiols (20–24), benzooxazole-2-thiols (25, 26), 1,3,4-thiadiazole-2-thiol (27), and thiazole-2-thiol (28) were obtained in 60–90% yields. Remarkably, our CuNiO₂ catalyst enabled the synthesis of these heterocyclic thioethers (20–28) in high yields without N/O/S chelation or catalyst deactivation, which represents a major advantage of this protocol.

Under the optimized reaction conditions RC-2, the functional group tolerance and substrate scope were evaluated by coupling various functionalized aromatic thiols (alkyl, amine, ether, hydroxy, halide, acetyl) with aryl iodides and bromides, affording the desired thioethers (29–44) in good-to-excellent yields without metal–sulfur chelation (Scheme 3). Both electron-donating (29–40) and electron-withdrawing (41–44) aryl halides gave the corresponding products in 70–95% yields. Notably, aryl halides bearing reducible functional groups, such as carbonyls (41–43) and nitro (44), were well tolerated, even in the presence of nickel. Electron-donating thiols (29–33) and electron-withdrawing thiols (34–36, 38–39, 41) also provided excellent yields, and products 41–43 were compatible with KOH as the base. The reactions were performed at 50 °C in a H₂O : DMSO (4 : 1) solvent system. These conditions are suitable for general aromatic thiols (RC-1 also gives good results), with reactivity following I ≫ Br; aryl chlorides and fluorides remained intact. The structure of (2-fluorophenyl)(4-methoxyphenyl)sulfane (39) was confirmed by single-crystal X-ray analysis (CCDC no. 2393842).

Scheme 3 Substrate scope of aromatic thiols with functional group compatibility. ^aCatalyst (5 mol%), aryl halide (1 mmol), thiol (1.2 equiv.), K₂CO₃ (1.5 equiv.), TBAB (1 equiv.) H₂O : DMSO in 4 : 1 ratio (1 mL) at 50 °C for 10 h, ^bisolated yield, ^cKOH, optimized reaction condition 2 (RC-2).

Application of the protocol for synthesis of bioactive molecules

Finally, we looked for meaningful application of this sustainable methodology (Schemes 4–6). All these applications confirmed for gram scale synthesis by using reaction condition (RC-1). Anti-cancer agents 45 and 46 (ref. 22) were synthesized from oxidation of bis(4-methoxy phenyl)sulfane (32) and 1-chloro-4-((4-methoxyphenyl)sulfonyl)benzene (34) with 30% H₂O₂ in glacial acetic acid respectively (Scheme 4).²³ The precursors 32 and 34 were synthesized by standard reaction condition (RC-1) in gram scale. Anti-breast cancer molecule 47 (ref. 24) was synthesized in 47% by cross-coupling of benzo-oxazole-2-thiol and 5-iodo-1,2,3-trimethoxybenzene using 5 mol% of CuNiO₂ catalyst under optimized conditions RC-1 (Scheme 4). Cathepsin D inhibitor analogue²⁵48 was synthesized from coupling of 4-nitrobromobenzene and benzothiazole-2-thiol with 90% yield under reaction condition RC-1 at 80 °C in water solvent, whereas the attempt to synthesize the same analogue was failed when we tried to couple 4-bromoaniline with benzoxazole-2-thiol and benzothiazole-2-thiol, instead afforded symmetrical dithioacetals 49a and 49b respectively (the structure is confirmed by XRD, CCDC 2377843, 2377844) in 42–45% yield (Scheme 5). K₂CO₃ is believed to be the source of methylene (CH₂) unit for dithioacetal.²⁶ Further, structure of product 1-chloro-4-((4-methoxyphenyl)sulfonyl)benzene (46) is confirmed by single-X-ray (CCDC no. 2388314).

Scheme 4 Synthesis of bioactive molecules (anti-cancer and cathepsin D inhibitor) using NiCuO₂ catalyst.

Scheme 5 Failed attempt for synthesis of precursor of cathepsin-D-inhibitor using NiCuO₂. ^aCatalyst (5 mol%), aryl bromide (1 mmol), thiol (1.2 equiv.), K₂CO₃ (1.5 equiv.), TBAB (1 equiv.) H₂O (1 mL) were stirred at 80 °C for 10 h, ^bisolated yield.

Scheme 6 Synthesis of precursor of anti-depressant, anti-bacterial scaffold, precursor of CB2 receptor, and HSD-1 inhibitor using NiCuO₂ catalyst.

Moreover, the synthesis of antibacterial precursor dapsone 50,²⁷ antimycobacterial analogue 51 (ref. 28) and anti-depressant agent 52 (analogue of vortioxetine)²⁹ were synthesized in good to excellent yield (90–95%) using reaction condition RC-1 at 80 °C (Scheme 6). Similarly, CB2 receptor agonist³⁰53 and 54 which are quinoline derivatives of thiol were synthesized by the reaction of corresponding aryl halides with thiols using reaction condition RC-1 at 80 °C. It is noteworthy that 2-bromoquinolines derivatives are difficult for coupling due to different electronic environment.²⁴ Finally, precursor of HSD-1 inhibitor 55 (ref. 31) was synthesized in 97% yield from the oxidation of 1-(4-((2-chlorophenyl) thio) phenyl) ethan-1-one (41) (Scheme 6).

DFT mechanistic studies

Based on optimized reaction conditions and control experiments, a plausible mechanism for C–S cross-coupling was proposed using enthalpy and energy profile by DFT calculation³² for the different intermediates formed during the reaction of 4-methoxybromobenzene and 2-fluorobenzene thiol under reaction condition 1 (see SI) the overall reaction is highly exergonic, with a calculated Gibbs free energy change (ΔG) of −102.7 kcal (Fig. 3). The active centre of the catalyst is more likely to be nickel instead of copper as evident from the enthalpy and energy profile. The mechanistic investigation involves five consecutive steps. In the first step, 2-fluorobenzene thiol reacts with K₂CO₃ to form the intermediate potassium 2-fluorobenzenethiolate (a3) along with the by-product H₂CO₃. In this acidic condition, CuNiO₂ catalyst (a0) releases its ring strain to give a2 and a2* (ΔG = −63.9 and −79.4 kcal mol⁻¹), which involves oxidative addition with aryl bromide (a1) to form the intermediate a4 with Cu and a4* with Ni. This step is endergonic with a free energy of −10.8 and −14.8 kcal mol⁻¹ for Cu and Ni, respectively. However, interaction of complex a4 and a4* with a3 affords thiol-bound intermediate (a5 and a5*), accompanied by the release of KBr (ΔG = −73.9 and −72.4 kcal mol⁻¹). Subsequently, complex a5 and a5* rearrange to give a6 with strong S–Cu interaction and weak S–Ni interaction. This step is exergonic with a free energy of −14.9 kcal mol⁻¹ for Cu–S complex, whereas it is −25.8 kcal mol⁻¹ for Ni–S complex a6*. The final step involves the release of C–S cross-coupled product (a7) and catalyst a2, a2*. This step is exothermic. Cu–S complex a6 releases −1.6 kcal mol⁻¹ energy for releasing the product and catalyst. However, Ni–S complex a6* releases product easily with loss of −4.4 kcal mol⁻¹ energy along with catalyst a6*. From the energy profile diagram, it is clear that the reaction at the Nickel centre is more preferred in comparison to copper. It is noteworthy that Cu alone is substantially more active than Ni (Table 1, entry 14–15). However, in the oxygen-bridged [Cu–O–Ni] catalyst, complex a6* may be stabilised by electron transfer from Cu²⁺ to Ni²⁺ through the oxygen bridge stabilising Ni(II) during reductive elimination; [Ni²⁺/Ni (E° = −0.25 V); Cu²⁺/Cu (E° = +0.34 V)].³³ A plausible mechanism is shown in Fig. 4.

Fig. 3 Energetic profile for the different intermediates formed during the reaction of 4-methoxybromobenzene and 2-fluorobenzene thiol under reaction condition 1. Quantum-chemical calculations were carried out with the Gaussian 16 program to examine the reaction mechanism. The equilibrium geometry of all species studied in this work and their vibrational frequency calculations were calculated with the B3LYP density functional theory, and the LANL2DZ basis set. We constructed a reaction pathway scheme (RPS) for possible reaction channels. All equilibrium geometries showed no imaginary frequencies, confirming their identity as true local minima. The energies are corrected for vibrational zero-point energy (ZPE). Solvent effects were included using the polarizable continuum model (PCM), with water. This was implemented using the SCRF = (SMD, solvent = water) as keywords. Thermochemical corrections, including Gibbs free energy and enthalpy, were computed.

Fig. 4 Plausible mechanism after DFT study (ΔG is described in kcal mol⁻¹).

Recyclability

The recyclability of the catalyst was evaluated using the coupling of 4-methoxyiodobenzene with adamantane thiol under RC-1 conditions. Upon completion of the reaction, 10 mL of ethyl acetate was added, and the organic layer was separated by centrifugation. The organic phase was then evaporated to isolate the desired product. The aqueous layer containing the catalyst was heated at 50 °C for 20 minutes, and the pH was adjusted to 11 using 0.5 M KOH, regenerating the catalyst as a black powder. Powder XRD analysis confirmed that the regenerated catalyst maintained its original structure (see SI for details). The catalyst was successfully reused for three consecutive cycles with negligible loss in yield: 93% (1st cycle), 92% (2nd cycle), and 91% (3rd cycle).

Conclusion

In summary, we have developed a novel oxygen-bridged bimetallic nano-catalyst, CuNiO₂, from inexpensive copper and nickel sources via an autoclave method. This catalyst efficiently promotes Csp²–S cross-coupling of thiols with aryl halides in water. It exhibits broad substrate tolerance, accommodating aryl, heteroaryl, and alkyl thiols with aryl and heteroaryl iodides under ligand-free conditions. The protocol enables the high-yield synthesis of complex hetero thioethers, providing a pathway for the preparation of bioactive compounds. Its applicability in aqueous medium has been demonstrated for the synthesis of motifs relevant to antimycobacterial, anticancer, and antidepressant agents, CB2 receptor agonists, as well as precursors of cathepsin-D inhibitors, HSD1 inhibitors, and dapsone. This approach offers a practical, environmentally benign, scalable, and reliable route to alkyl and aryl (hetero) sulfides with potential applications in the development of therapeutics. The crucial role of synergistic Cu–Ni catalysis has been supported by control experiments and DFT studies. DFT study revealed that the catalyst is more likely to be nickel instead of copper, as evident from the enthalpy and energy profile.

Experimental section

Procedure for synthesis of CuNiO₂ catalyst

Cu(OAc)₂·H₂O (1 mmol, 199 mg) is dissolved in 50 mL of warm distilled water. In another beaker NiCl₂·6H₂O (1 mmol, 236 mg) is dissolved in 50 mL of warm distilled water. The later solution was added dropwise to first beaker dropwise. The solution was heated at 50 °C for 10 minutes to get a sky colour gummy solution. Next, 25 mL of 2 N KOH solution was added drop wise till the pH of solution is 11. The colour of solution gradually changed to black colour. The whole solution transferred into a Teflon lined hydrothermal autoclave and that kept in an oven at 150 °C for 24 h. The catalyst was washed repeatedly with 100 mL of distilled water and then 50 mL of ethanol by using REMI C-24 centrifuge instrument and then dried in an oven at 70 °C for 12 h. The catalyst was characterized in TEM, SEM, EDX, IR, Powder XRD and XPS.

Procedure for C–S cross-coupling reaction

To an oven dry glass vial (5 mL) equipped with a magnetic bead, CuNiO₂ (5 mol%), water 1 mL for RC-1 and water (0.8 mL) + DMSO (0.2 mL) for RC-2, TBAB (1 equiv.), haloarenes (1 mmol), corresponding thiols (1.2 equiv.) and base K₂CO₃ (1.5 equiv.) in air was added (adding sequence should be followed strictly). The reaction mixture was placed in a pre-heated oil bath maintained at 80 °C (for RC-1), and 50 °C (for RC-2). The reaction was monitored with TLC and KMnO₄ stain. After the required time, the reaction mixture was quenched with NH₄Cl solution (5 mL) and extracted with EtOAc (3 × 10 mL). The organic layer was dried over sodium sulfate, filtered and evaporated by rotor. The residue was purified via flash column chromatography (n-hexane and ethyl acetate).

Author contributions

A. Swain conceptualized and synthesized the catalyst and investigated all reactions. Dr. L. Rout and Prof. Debendra K. Mohapatra written the manuscript. B. Behera helped in the DFT calculation. S. L. Samal measured provided XRD of molecules and characterised the catalyst.

Conflicts of interest

The authors declare no conflicts of interest.

Data availability

The data supporting this article have been included as part of the supplementary information (SI). Supplementary information is available. See DOI: https://doi.org/10.1039/d5cy01377a.

CCDC 2377843, 2377844, 2388312, 2388314, 2393842, and 2393839 contain the supplementary crystallographic data for this paper.^34a–f

Acknowledgements

Prof. Laxmidhar Rout acknowledges Anusandhan National Research Foundation (ANRF) SERB India, CRG/2022/001544 New Delhi, Council of Scientific and Industrial Research, CSIR/02/0393/21/EMR-II New Delhi, India for generous funding. Thanks to UGC and Berhampur University for the infrastructure facilities. Prof. Debendra K. Mohapatra gratefully acknowledges the ANRF, New Delhi (SERB) [SERB/CRG/2022/002490], for financial support and the Director, CSIR-IICT as well as the Director, IISER Berhampur for providing a conducive research environment and state-of-the-art infrastructural facilities.

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