title: Probing the solvent dependent photophysics of fac-[Re(CO)3(dppz-X2)Cl] (dppz-X2 = 11,12-X2-dipyrido[3,2-a:2',3'-c]phenazine); X = CH3, H, F, Cl, CF3).
abstract: The results of electrochemical measurements, density-functional theory calculations, emission and time-resolved IR (TRIR) spectroscopic studies for fac-[ReCl(CO)3(dppz-X2)], (dppz = dipyrido[3,2-a:2',3'-c]phenazine; X = CH3, H, F, Cl, CF3) are reported. For all complexes the calculations show that the lowest unoccupied molecular orbital (LUMO) is a phenazine based orbital localized on the dppz ligand. We observe that three different excited states, IL pi pi*, metal-to-ligand charge-transfer (MLCT) (phen), and MLCT (phz), are formed depending upon the substituent on the dppz ligand and on the nature of the solvent. This means that both the energy and the nature of the photophysically active state(s) can be tuned by both chemical modification of dppz ligand and solvent properties. The excited-state dynamics in these systems is directly related to the mechanism of the "light switch effect", and ps-TRIR has allowed a deeper insight into this mechanism by being able to directly monitor the change in the population of the higher lying emissive phen-type (3)MLCT and IL pi pi* states and the dark (3)MLCT (phz) state depending on the different environmental factors.
authors.affiliation: School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, UK.
authors.forename: Marina K
authors.initials: MK
authors.lastname: Kuimova
authors.forename: Wassim Z
authors.initials: WZ
authors.lastname: Alsindi
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Blake
authors.forename: E Stephen
authors.initials: ES
authors.lastname: Davies
authors.forename: Daniele J
authors.initials: DJ
authors.lastname: Lampus
authors.forename: Pavel
authors.initials: P
authors.lastname: Matousek
authors.forename: Jonathan
authors.initials: J
authors.lastname: McMaster
authors.forename: Anthony W
authors.initials: AW
authors.lastname: Parker
authors.forename: Michael
authors.initials: M
authors.lastname: Towrie
authors.forename: Xue-Zhong
authors.initials: XZ
authors.lastname: Sun
authors.forename: Claire
authors.initials: C
authors.lastname: Wilson
authors.forename: Michael W
authors.initials: MW
authors.lastname: George