The design, synthesis and anticancer properties of a series of Ag(i), Au(i) and Au(iii)–NHC complexes supported by pyridyl[1,2-a]{2-acetylylphenylimidazol}-3-ylidene are described.

Starting from proligand 1-methyl-2-(phenyl)imidazo[1,5-a]pyridine-2-iumchloride (1.HCl), 1-methyl-2-(phenyl)imidazo[1,5-a]pyridine silver(I) chloride, (2) has been prepared. Synthesis, structures and photophysical properties of (2,2 / −bipyridyl)-1-methyl-2-(phenyl)imidazo[1,5-a]pyridinesilver(I) hexaflurophosphate, (3), 1-methyl-2-(phenyl)imidazo[1,5-a]pyridinesilver(I) carbazolate, (4) and 1-methyl-2-(phenyl)imidazo[1,5-a]pyridinegold(I)carbazolate, (5) are focused. Herein we have first reported the NHC-Ag-(bpy/carbazole). All the complexes have been characterized by elemental analysis, various spectroscopic studies and finally screened for luminescent properties. All the complexes are strongly emissive. Solid state structures of 2, 3, 4 and 5 have been determined by X-ray diffraction studies. Conventionally, complex 2 adopts linear geometry whereas complex 3 embraces triangular planar geometry around Ag; complex 4 and 5 clinches linear geometry around Ag/Au. All the complexes absorb light within 275-343 nm. Complex 3 is luminous at~407 mn, whereas complex 4 and 5 luminous at~360 nm having short life time 1.00-6.97 ns. The quantum yield (Φ em) of the complexes varies 0.106-0.186. It is expected variation of luminescence arises due to change of metal and the chromophore (bpy/carbazole). Density Functional Theory (DFT) and Temparature Dependent Density Functional Theory (TDDFT) calculations were performed to verify crystallographically derived parameters and to calculate the UV-Vis properties of the ground state as well as of the first excited state of the complexes.

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Two annulated imidazolium salts, 2‐(phenyl)imidazo[1,5‐a]pyridin‐4‐ylium hexafluorophosphate 1⋅H(PF6) and 1‐methyl‐2‐(phenyl)imidazo[1,5‐a]pyridin‐4‐ylium hexafluorophosphate 2⋅H(PF6), were synthesized via formylative cyclization of the corresponding Schiff bases followed by anion metathesis with KPF6. Independently treating 1⋅H(PF6) or 2⋅H(PF6) with silver oxide and then palladium chloride in acetonitrile led to the formation of the complexes [Pd(1)2Cl(CH3CN)]PF6 (1 a) and [Pd(2)2Cl(CH3CN)]PF6 (2 a), respectively. Likewise, [Pt(1)2Cl(CH3CN)]PF6 (1 b) and [Pt(2)2Cl(CH3CN)]PF6 (2 b) were synthesized using similar transmetallation chemistry. The complexes were characterized using various spectroscopic techniques and the solid state structures of 1‐H(PF6) as well as 2 a were elucidated using X‐ray diffraction analyses. A series of DFT calculations were also performed to gain further insight into the respective structures of the complexes. Complexes 1 a and 2 a were found to facilitate Suzuki coupling reactions under relatively mild conditions.