Ultrafast Luminescence Decay and Intersystem Crossings in rhenium (I) complexes: DFT Method

The interpretation of ultrafast intersystem crossing (ISC) processes in transition of metal complexes through the destruction of femtosecond luminescence, which is a challenging issue in quantum chemistry, is presented. To understand this photophysical phenomenon, explicit consideration of the spin orbitcoupling (SOC) is necessary. So far little studies have been done, and especially on heavy metal compounds with heavy elements such as Rhenium [1]. complexes, a new series of chromophoric ligands based upon the fused imidazo[4,5-f]-1,10-phenanthroline core that are functionalised with different substituted aryl groups [2] were used. These type complexes are often ascribed to metal-to-ligand charge transfer (MLCT) excited states. Such complexes have found application in the design of chemosensors and cell imaging agents [3]. The optimization of excited states, as well as the absorption wavelength and oscillator strength was done using the TD-DFT method, with the triple-ξ base set in the Gaussian 09 Linux. The results show that the agreement with experiment is quite good. Finally, the luminescence spectrum was plotted and the results were analyzed. The wavelength of maximum excited state energy at 584.03 nm and oscillator strength £=0.0005 is attributed to the S1 state in complex and in the experimental data excited state energy shown at 580 nm.