Nickel nanoparticle-decorated phosphorous-doped graphitic carbon nitride (Ni@g-PC3N4) was synthesized and used as an efficient photoactive catalyst for the reduction of various nitrobenzenes under visible light irradiation. Hydrazine monohydrate was used as the source of protons and electrons for the intended reaction. The developed photocatalyst was found to be highly active and afforded excellent product yields under mild experimental conditions. In addition, the photocatalyst could easily be recovered and reused for several runs without any detectable leaching during the reaction.

Iron(ii) bipyridine grafted on graphitic carbon nitride (Fe(bpy)3/npg-C3N4) was found to be an efficient photocatalyst for oxidative coupling of benzyl amines using molecular oxygen as an oxidant and a household white LED as a light emitting source.

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A photoactive bimetallic complex comprising a photosensitizer ruthenium unit and a catalytic Mn­(I) unit connected via a bipyrimidine (bpm) bridging ligand is prepared and used for the first time for developing a light induced copper catalyzed [3 + 2] azide–alkyne “click” (CuAAC) reaction for the formation of 1,2,3-triazoles under visible light irradiation. The developed bimetallic complex exhibited enhanced activity as both the photosensitizer ruthenium unit as well as manganese catalyst unit are attached in a single molecule, providing efficient electron transfer for the photochemical reduction of Cu­(II) to Cu­(I) in situ which subsequently was used for the cycloaddition of azides with terminal alkynes to give 1,4-disubstituted 1,2,3-triazoles in the presence of triethylamine as a sacrificial donor.

A novel in situ synthesized Ru(bpy)3/TiO2 hybrid nanocomposite is developed for the photoreduction of CO2 into methanol under visible light irradiation. The prepared composite was characterized by means of SEM, TEM, XRD, DT-TGA, XPS, UV-Vis and FT-IR techniques. The photocatalytic activity of the synthesized hybrid catalyst was tested for the photoreduction of CO2 under visible light using triethylamine as a sacrificial donor. The methanol yield for the Ru(bpy)3/TiO2 hybrid nanocomposite was found to be 1876 μmol g(-1) cat (ϕMeOH 0.024 mol Einstein(-1)) that was much higher in comparison with the in situ synthesized TiO2, 828 μmol g(-1) cat (ϕMeOH 0.010 mol Einstein(-1)) and the homogeneous Ru(bpy)3Cl2 complex, 385 μmol g(-1) cat (ϕMeOH 0.005 mol Einstein(-1)).

Heterostructured tin phthalocyanine supported to mesoporous ceria was synthesized and used a photocatalyst for CO 2 reduction under visible light. The photoreduction CO 2 activities of the heterostructures were investigated in the presence of triethylamine as sacrificial agent. The developed photocatalyst exhibited high catalytic activity for photoreduction of CO 2 and after 24 hours of visible light irradiation 2342 mmol g À1 cat of methanol (f MeOH ¼ 0.0223 or 2.23%) and 840 mmol g À1 cat of CO (f CO ¼ 0.0026 or 0.26%) were obtained as the major reaction products. The methanol formation rate (R MeOH ) and CO formation rate (R CO ) was found to be 97.5 mmol h À1 g À1 cat and 35.0 mmol h À1 g À1 cat respectively. While under the identical experimental conditions mesoporous ceria (meso-CeO 2 ) gave only 316 mmol g À1 cat of methanol (f MeOH ¼ 0.003 or 0.30%) and 126 mmol g À1 cat CO (f CO ¼ 0.0004 or 0.04%) with product formation rate R MeOH ¼ 13.2 mmol h À1 g À1 cat and R CO ¼ 5.3 mmol h À1 g À1 cat.Furthermore, the recovered catalyst showed consistent catalytic activity for at least five runs without any significant loss in product yields.

Experimental and theoretical 13 C kinetic isotope effects (KIEs) are utilized to obtain atomistic insight into the catalytic mechanism of the Pd(PPh 3 ) 4 -catalyzed Suzuki-Miyaura reaction of aryl halides and aryl boronic acids. Under catalytic conditions, we establish that oxidative addition of aryl bromides occurs to a 12-electron monoligated palladium complex (Pd-(PPh 3 )). This is based on the congruence of the experimental KIE for the carbon attached to bromine (KIE C−Br = 1.020) and predicted KIE C−Br for the transition state for oxidative addition to the Pd(PPh 3 ) complex (1.021). For aryl iodides, the near-unity KIE C−I of ∼1.003 suggests that the first irreversible step in the catalytic cycle precedes oxidative addition and is likely the binding of the iodoarene to Pd(PPh 3 ). Our results suggest that the commonly proposed oxidative addition to the 14-electron Pd(PPh 3 ) 2 complex can occur only in the presence of excess added ligand or under stoichiometric conditions; in both cases, experimental KIE C−Br of 1.031 is measured, which is identical to the predicted KIE C−Br for the transition state for oxidative addition to the Pd(PPh 3 ) 2 complex (1.031). The transmetalation step, under catalytic conditions, is shown to proceed via a tetracoordinate boronate (8B4) intermediate with a Pd−O−B linkage based on the agreement between an experimental KIE for the carbon atom involved in transmetalation (KIE C-Boron = 1.035) and a predicted KIE C-Boron for the 8B4 transmetalation transition state (1.034).

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