Influence of ancillary ligands on the photophysical properties of cyclometalated organoplatinum(ii) complexes

Abstract

The photophysical properties of three series of cyclometalated organoplatinum(ii) complexes were studied and the influence of changing the ancillary ligands and substituents on their luminescence properties were investigated.

Cyclometalated Platinum(II) Complexes Simultaneously Catalyze the Cross-Linking of Polysiloxanes and Function as Luminophores

“…All the complexes exhibit a structured emission band profile with vibronic progression, and these observations together with the literature data (including the data for cyclometalated platinum­(II) complexes bearing isocyanide ligands , ) indicate that, in 2 and 5 , the CNCy and PPh 3 orbitals do not contribute to the radiative excited state, and the emission can be assigned to a metal-perturbed 3 LC intraligand (ppy) transition with a small admixture of 3 MLCT. In agreement with the mixed 3 LC/ 3 MLCT assignment, the emission λ max of 3 is similar to those of 2 and 5 .…”

“…The 31 P­{ 1 H} NMR spectrum of 5 in CDCl 3 exhibits two singlets at δ P 17.43 ( J Pt,P = 3780 Hz) and 25.31 ppm ( J Pt,P = 1689 Hz) (integral ratio of 7:1), which correspond to the two P atoms of the PPh 3 ligands, and these signals are flanked by 195 Pt satellites, thus confirming the existence of the Pt II –PPh 3 linkage. The geometric configurations of these isomers can be determined by analyzing the P,Pt coupling constants. − The large value of J ( 195 Pt– 31 P) for the resonance of the major isomer (δ P 17.43 ppm, J Pt,P = 3780 Hz) is typical for a phosphine P atom in the trans position relative to the N center of C , N -cyclometalated ligands, − whereas the coupling constant of the minor isomer signal (δ P 25.31 ppm, J Pt,P = 1689 Hz) is characteristic of phosphines located trans to the Pt-bound C atom. , Refluxing 5 in CHCl 3 (or in CDCl 3 ) for 3 h does not change the isomeric ratio. The ground-state trans effect of PPh 3 is greater than that of CNCy, , and this difference enables the stabilization of the trans -(C ppy , C CNCy ) form of 5 in the solid state.…”

A C^N Cycloplatinated(II) Fluoride Complex: Photophysical Studies and Csp3–F Bond Formation

“…While transition-metal complexes with Cl, Br, and I ligands are very common, the F-containing analogues are much less available, especially for late-transition-metal cations in low oxidation states, − thus preventing a complete study across the group. For example, halide ligands (Cl, Br, and I) have been shown to largely influence the emission properties of Pt­(II), − Pt­(IV), , and Cu­(I) − complexes. The scarcity of transition-metal fluoride complexes is largely due to their high reactivity and limited synthetic methods, as predicted by the hard/soft acid–base theory that the fluoride ion (hard base) is mismatched with soft acids such as Pt­(II), Pd­(II), and Au­(I) …”

DFT/TD-DFT study of electronic and phosphorescent properties in cycloplatinated complexes: implications for OLEDs

“…There is substantial experimental information regarding the chemical and spectroscopy properties such as structural properties determined by X-ray diffraction methods and UV-vis spectra of selected systems. 21–24,26,28–32 In this work, we focus on the suitability of 1–5 to be used in OLED devices.…”