Synthesis and properties of [Pt(4-CO 2CH 3-py) 2(dmit)] and [Pt(4-NO 2-py) 2(mnt)]: Exploring tunable Pt dyes

• Published in: Polyhedron 2009-12, Vol.28 (18), p.4084-4090
• Main Authors: Moorcraft, Lucy P., Jack, Lorna A., Jennings, James R., Peter, Laurence M., Yellowlees, Lesley J., Robertson, Neil
• Format: Article
• Language: English
• Subjects: DFT; Dithiolate; Electrochemistry; Pyridyl; Solar cells
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2009.09.017

Square-planar Pt complexes have been prepared and show separate tuning of the HOMO and LUMO orbitals through modification of the dithiolate (HOMO) and pyridyl (LUMO) ligands, respectively. This is evidenced by voltammetry, hybrid DFT calculations, UV/Vis spectroelectrochemistry and in situ EPR spectroelectrochemistry. Two [Pt(II)(substituted-pyridyl) 2(dithiolate)] dyes with the formulas [Pt(4-CO 2CH 3-py) 2(dmit)] and [Pt(4-NO 2-py) 2(mnt)] (where py = pyridyl, dmit = 1,3-dithiol-2-thione-4,5-dithiolate and mnt = maleonitriledithiolate) and their dichloride precursors [PtCl 2(4-R-py) 2] have been synthesized and compared to a previously-reported dye [Pt(4-CO 2CH 3-py) 2(mnt)]. Variation of either the pyridyl ligands or the ditholate ligand showed tuning of the electrochemical and spectroscopic characteristics of the dyes as evidenced by cyclic and differential pulse voltammetry, hybrid DFT calculations, UV/Vis spectroelectrochemistry and in situ EPR spectroelectrochemistry. The HOMO was shown to be mostly dithiolate based and the LUMO pyridyl based allowing absorption characteristics to be predictably tuned to longer wavelengths, which is important for optimization of such dyes in applications such as solar energy conversion.