Spectroscopic, structural and DFT studies of luminescent Pt(II) and Ag(I) complexes with an asymmetric 2,2 '-bipyridine chelating ligand

15th International Conference on Molecular Spectroscopy (ICMS) - From Molecules to Molecular Materials, Biological Molecular Systems and Nanostructures -- SEP 15-19, 2019 -- Wojanow, POLANDColes, Simon/0000-0001-8414-9272WOS: 000587468000096A new unsymmetrically substituted 2,2'-bipyridine ligand, 5-methyl-5'-carbomethoxy-2,2'-bipyridine (L) was isolated from the dry distillation of the copper(II) complex, mono-aqua-bis(trans-5-methyl-pyridine2-carboxylato- N,O)copper(II). the ligand was fully characterized. the spectroscopic and single-crystal Xray diffraction (SCXRD) studies of the coordination compounds of the ligand with platinum(II) and silver(I); cis-Pt(L)Cl-2 (1) and [Ag(L)(2)]PF6 (2), respectively are reported. in 1, the Pt centre coordinates to tertiary N atoms of the ligand and two chloride ions to form a neutral square-planar coordination sphere, while in 2, the Ag(I) centre is coordinated by two ligands through N atoms to generate a cationic flattened tetrahedron geometry in which two mean planes intersect each other at 50.93 degrees. the pyridine rings are nearly coplanar as revealed by the torsion angle of N2-C7-C6-N1 1.32(5)degrees. in both complexes, L acts as a chelating ligand through pyridyl N atoms. in 1, the molecular units are stacked in a head-to-tail fashion with a Pt center dot center dot center dot Pt separation of 3.5 degrees A. Supramolecular self-assembly of the molecular units by extensive intermolecular contacts through C-H center dot center dot center dot Cl and C-H center dot center dot center dot O between the adjacent units results in an infinite two-dimensional flattened-out herringbone structure in the crystalline state. in 2, the molecular units are interconnected with each other by C-H center dot center dot center dot O contacts between the adjacent units running parallel to each other. Both complexes are fluorescent in solution and have emission maxima in the UV-Vis regions, which is a very important property for optoelectronic applications. DFT (density functional theory) and TD-DFT (time-dependent-DFT) calculations were performed at B3LYP/6-311+G(d,p)/LANL2DZ level to explore structural, electronic, and spectroscopic properties to compare with the experimental results. the molecular orbitals (MOs) were carried out with DFT at the same level. (C) 2020 Elsevier B.V. All rights reserved.Polish Acad Sci, Inst Low Temp & Struct ResTurkish Scientific and Technical Research CouncilTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [TBAG-2450 (104T060)]; Zonguldak Bulent Ecevit UniversityBulent Ecevit University [2007/3-13-02-01]; UK Engineering and Physical Sciences Research CouncilEngineering & Physical Sciences Research Council (EPSRC)The authors are grateful to the Turkish Scientific and Technical Research Council [TBAG-2450 (104T060)] and also Zonguldak Bulent Ecevit University for grant 2007/3-13-02-01. the authors also wish to acknowledge the UK Engineering and Physical Sciences Research Council for funding the National Crystallography Service. Computer time provided by Fen Cluster (Ege University Faculty of Science) and TUBITAK ULAKBIM TRUBA Resources is gratefully acknowledged