Platinum(II) Terpyridyls: Excited State Engineering and Solid-State Vapochromic/Vapoluminescent Materials

The present thesis describes the synthesis and photophysical properties of a variety of organometallic Pt^II complexes containing mainly CT excited states. The photophyscial properties have been investigated by absorption spectroscopy, steady-state and time resolved photoluminescence both at room temperature and 77 K, nanosecond laser flash photolysis, and cyclic voltammetry. This thesis focused in complexes with the molecular structure [(tpy)PtR]⁺, where R is either Cl^- or a substituted acetylide unit (-C≡CR') and tpy corresponds to 2,2':6',2"-terpyridine. Through out this work, it can be found that the tpy unit has different substitutions, from tert-butyl groups to avoid stacking and promote solubility, to acetylide groups in the 4'-position of the tpy core to investigate the electronic influence of these groups.

All the platinum complexes studied exhibit photoluminescence in fluid solution at room temperature emanating from a CT excited state. In some cases, the excited state is described as an admixture of close-lying excited states (³CT and ³IL). Based on DFT calculations, it is believed that the CT excited state in these complexes possess metal-toligand (MLCT) character as well as ligand-to-ligand (LLCT) character. At low temperature, an increase in the excited state lifetime is observed in every case accompanied by a change in the shape of the emission profile, suggesting a change in the excited state upon cooling of the systems. All the complexes under study demonstrated to have the ability to sensitize singlet oxygen, due to their long-lived triplet excited states.

The sensory application of Pt^II complexes is also reported. A series of terpyridyl Pt(II) chloro complexes with different counterions and substitutions on the tpy core were incorporated into microarrays and their pattern response to different volatile organic vapors (VOC’s) was analyzed.