'Optimized route' to synthesize isoelectronic and isostructural Au()- and Pt()-NHC complexes: synthesis, structure, spectral properties, electrochemistry, and molecular docking studies

We report the synthesis, structures, luminescent properties, and electrochemistry of gold( iii ) and platinum( ii )-N-heterocyclic carbene complexes. The proligand 1-methyl-2-(pyridylmethyl)imidazo[1,5- a ]pyridin-4-ylium hexafluorophosphate, ( 1 ·HPF 6 ), and two novel isoelectronic and isostructural complexes, viz. [Au( 1 ) 2 ][PF 6 ] 3 ( 2 ), [Pt( 1 ) 2 ][PF 6 ] 2 ( 3) , were synthesized and characterized by several spectroscopic studies. Finally, the single crystal X-ray diffraction studies established the square planar geometry of both complexes 2 and 3 . The solid state structures of both the square planar complexes revealed two C carbene and two N pyridine present in trans fashion around the central metal ions. The complexes showed strong absorbance at ∼350 nm and DFT studies demonstrated the ILCT transition. Both complexes are luminescent at ∼400 nm. DFT and TDDFT studies were performed to gain insights into the experimental findings of solid-state structures and electronic properties. Electrochemical studies of Au( iii )-NHC complex 2 showed two irreversible Au( iii ) → Au( i ) and Au( i ) Au(0) reductions at −0.75 V and 1.28 V, whereas Pt( ii )-NHC complex 3 revealed Pt( ii / iv ) two-electron reversible oxidation potential at 0.53 V. Molecular docking analysis revealed the highest free binding energy for complex 3 with human-DNA topoisomerase as compared to complex 2 and proligand 1 ·HPF 6 . Pharmacokinetics studies revealed the scope of the complexes to be potent drugs. Synthesis, structures, luminescent properties, electrochemistry, and molecular docking of isoelectronic and isostructural Au( iii )- and Pt( ii )-NHC complexes have been described.