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Achieving photocatalytic organic transformation reactions by using a visible light induced semiconductor-based photocatalyst is promising as a green and sustainable approach. In the present study, Au/Pd bimetallic alloy loaded amine (APTES) functionalised LDH (Layered double hydroxide)–MCM-41 composite was prepared through an in situ co-precipitation followed by a co-reduction method. The structural phases, textural properties, optical behaviour, morphological aspects, chemical states and functional groups of the photocatalysts were thoroughly analysed by powder X-ray diffraction (PXRD), high-resolution transmission electron microscopy (HRTEM), ultraviolet-visible diffuse reflectance (UV-vis DRS), fourier-transform infrared (FTIR) and X-ray photoelectron (XPS) spectroscopies. Moreover, the formation of an alloying structure between Au and Pd was confirmed from PXRD, HRTEM and UV-vis absorption spectra. We investigated one-pot synthesis of imines through photoalkylation of benzyl alcohol with nitrobenzene over Au/Pd bimetal alloy loaded on amine functionalised LDH–MCM-41 composite and it demonstrated imine yield of around 3.1 times (68%) more than the parent LDH (22%). The alloy nanoparticless efficiently harvest light and possess higher photocatalytic activity with respect to single Pd and Au nanoparticles. Due to the alloying structure develops charge heterogeneity on the surface of alloyed nanoparticles and enhances the interaction between metal surface with substrate molecule which promotes the coupling between photo generated benzaldehyde with aniline to form imine. Characterisation such as photoluminescence (PL), time-resolved photoluminescence (TRPL), electrical impedance spectroscopy (EIS) and photocurrent density measurements further proved the superior photoactivity towards imine synthesis. These photocatalytic tandem reactions, therefore, have great potential as an effective pathway for the one-pot organic synthesis and transformation of organics in an environmentally friendly way.

Visible light harvesting by heterogeneous photocatalysts and their applications in organic transformation reactions for the synthesis of target molecules are quite demanding science in the current scenario. In this regard, herein, a novel metal (Au/Pd)-functionalized metal organic framework (UiO-66-NH2) was synthesized to carry out the Suzuki–Miyaura coupling (SMC) reaction under visible light irradiation at ambient conditions. In order to justify the claim regarding the formation of alloys, crystallinity, morphology, particle size, proper separation of excitons, elemental content and their environment, various sensitive characterization techniques such as XRD, XPS, HRTEM, BET surface area and UV-vis analysis were employed. A mechanistic approach by means of experimental investigations revealed that the strong LSPR effect of Au facilitated the transfer of electrons to the Pd surface to make the surface negatively charged and suitable for the activation of aryl halides. The formed electropositive Au nanoparticles were converted to Au0 by accepting the photo-induced electrons from pristine UiO-66-NH2 and made available only holes at VB for the activation of phenylboronic acid. Among all the synthesized photocatalysts (1 : 2), Au/Pd@UiO-66-NH2 showed the highest activity (>99%) with TOF = 426 h−1 in an EtOH/H2O medium towards the SMC reaction, and the highest activity of this catalyst was supported by the electron gas model, LSPR effect (UV-vis) and active species separation (PL) analysis. The bimetallic noble nanoparticle-anchored UiO-66-NH2 not only expands the synthesis scope of C–C coupling by the SMC reaction under ambient conditions but will also inspire the further exploration of the activation of various reactants towards a wide range of organic transformation reactions.

Photocatalytic organic transformations driven by functionalised metal organic frameworks (MOFs) are a green perspective for fine chemical synthesis. In the class of highly porous materials, MOFs are unparalleled in their degree of tunability and structural diversity and range of physical and chemical properties such as large surface area, permanent porosity, large void volumes, and framework flexibility, because of which they can act as a sustainable alternative for inorganic semiconductors. MOFs are the latest class of ordered porous solids being intensively studied as a novel class of hybrid organic–inorganic materials as nanophotocatalysts in the field of chemistry, materials science, chemical engineering, etc. Although the photocatalytic application of MOFs is still in the early stages compared with their other applications such as gas storage, separation, and heterogeneous catalysis, the currently available results have revealed that functionalised MOFs are very active as photocatalysts. The present review aims to discuss the various synthetic methods, post-synthetic modifications, MOF catalysed organic reactions and proposed mechanistic pathways for photoinduced organic transformations.

This work reports an amine modified meso Al2O3@MCM-41, particularly the ordered mesoporous silica, as a catalyst for the formylation of amines with carbon dioxide (CO2) and with dimethylamine-borane (DMAB) as a green reducing source. This newly developed catalytic system represents a heterogeneous and environmentally benign protocol. Besides this, the catalyst could be reused for five consecutive cycles without any significant loss in its catalytic activity towards the synthesis of formamides. The amine modified meso Al2O3@MCM-41 catalysts were well characterized by high and low angle XRD, temperature programmed desorption (TPD), BET-surface area, TGA/DTA and FT-IR analysis techniques. The effect of various reaction parameters such as temperature, CO2 pressure, time and the ratio of substrates to DMAB for the synthesis of formamides has been investigated. The developed protocol can be applicable for the synthesis of most important key intermediates like formoterol, orlistat, leucovarin and iguratimod in biologically active compounds.