Phosphorescent Platinum(II) Complexes Featuring Chelated Acetoxime Pyrazoles: Synthetic, Structural, and Photophysical Study

Abstract

Treatment of cis-[PtCl 2 (Me 2 SO) 2 ] with the pyrazole acetoximes p-RC 6 H 4 {CN(H)NCCH}CH 2 C(Me)=NOH (R=OMe, H, F, Cl, CN, NO 2 ), prepared by a cascade reaction from the vinyl isoxazoles p-RC 6 H 4 C(H)=C(H){CONCC(NO 2 )}Me, leads to the complexes [PtCl 2 (Ar{CN(H)NCCH}CH 2 C(Me)=NOH)] (71-88 %). The complexes exhibit solid state room temperature phosphorescence with emission maxima in the region of 644-691 nm and biexponential relaxation with t 1 % 2 ms and t 2 % 0.32 ms. In the platinum compounds, substituents R affect phosphorescence quantum yields, which increase by one order of magnitude on going from electron acceptor (R = NO 2 ; 0.2 %) to electron-donor groups (R = OMe; 2.0 %). Based upon theoretical TD-DFT calculations using the CAMÀB3LYP functional, the absorption spectra were attributed to metal-to-ligand charge transfer ( 1 MLCT) and ligand-to-ligand charge transfer ( 1 LLCT) processes. The pyrazole acetoximes and their complexes were characterized by elemental analyses (C, H, N), HRESI-MS, FTIR, 1 H NMR (for metalfree species), and CP-MAS TOSS 13 C{ 1 H} NMR (for the platinum complexes). In addition, two complexes were studied by singlecrystal X-ray diffraction.[a] Dr.

Computational Studies of the Excitonic and Optical Properties of Armchair SWCNT and SWBNNT for Optoelectronics Applications

“…The spectrum of SWBNNT presented in Figure 6a shows only one peak, which occurred at 0.7 eV in the perpendicular direction. This peak was a result of transitions between optical-electronic states [34]. Zero peaks can be seen in the parallel direction, which justifies zero absorption.…”

“…These two peaks demonstrate the strong absorption properties of (5, 5) SWCNT in both the UV and visible regions. To further confirm the absorption behaviors of these two nanotubes, we studied the optical properties of the (5, 5) form of both SWCNT and SWNNT via a simulation of UV-Vis [34] spectra. The results are presented in Figure 7a,b.…”