Probing the use of long lived intra-ligand π-π^* excited states for photocatalytic systems: A study of the photophysics and photochemistry of [ReCl(CO)₃(dppz-(CH₃)₂)]

详细信息    查看全文

• 作者：Peter A. Summers^a ; ^b ; ^{Peter.Summers@nottingham.edu.cn} ; James A. Calladine^a ; Nasiru Ibrahim^b ; Kennedy P. Kusumo^b ; Charlotte A. Clark^a ; Xue-Z. Sun^a ; Michelle L. Hamilton^a ; ^c ; Michael Towrie^c ; ^d ; Jonathan McMaster^a ; Martin Schrö ; der^a ; ^e ; Michael W. George^a ; ^b ; ^{Mike.George@nottingham.ac.uk}
• 关键词：MLCT ; metal-to-ligand charge transfer ; FTIR ; Fourier transform infrared ; TRIR ; time-resolved infrared ; IL ; intra-ligand ; LUMO ; lowest unoccupied molecular orbital ; DNA ; deoxyribonucleic acid ; bpy ; 2 ; 2&prime ; -bipyridine ; dppz ; dipyrido[3 ; 2-a ; 2&prime ; 3&prime ; -c]phenazine ; dppz-(CH3)2 ; 11 ; 12-dimethyl-dipyrido[3 ; 2-a ; 2&prime ; 3&prime ; -c]phenazine ; [NiFe2] ; [Ni&lsquo ; S4&prime ; Fe2(CO)6] cluster (&lsquo ; S4&prime ;   ; =  ; (CH3C6H3S2)2(CH2)3) ; i-Pr-PyCa ; pyridine-2-carbaldehyde N-isopropylimine ; dapa
• 刊名：Polyhedron
• 出版年：2017
• 出版时间：17 February 2017
• 年：2017
• 卷：123
• 期：Complete
• 页码：259-264
• 全文大小：933 K
• 卷排序：123

文摘

We report the excited state photophysics and photochemistry of [ReCl(CO)3(dppz-(CH3)2)] (dppz-(CH3)2 = 11,12-dimethyl-dipyrido[3,2-a:2′,3′-c]phenazine) in CH3CN using time-resolved infrared (TRIR) and Fourier transform infrared (FTIR) spectroscopy. Excitation of the 1MLCT (metal-to-ligand charge transfer) band of [ReCl(CO)3(dppz-(CH3)2)] populates a 3MLCT excited state which rapidly interconverts on a timescale <1 ns to a long lived IL (intra-ligand) ππ∗ excited state with a lifetime of 190 ( ± 5) ns. In the presence of an electron donor (NEt3), the IL excited state of [ReCl(CO)3(dppz-(CH3)2)] can be reductively quenched to [ReCl(CO)3(dppz-(CH3)2)]− with the radical in the latter localised on the distal phenazine (phz) portion of the dppz ligand. The phz based electron in [ReCl(CO)3(dppz-(CH3)2)]− has minimal interaction with the rhenium metal centre which increases the stability of the photosensitiser in its reduced form. In non-dried, non-degassed CH3CN (1 M NEt3), [ReCl(CO)3(dppz-(CH3)2)]− shows no significant change in the carbonyl region of the IR spectrum for at least 2 h during continuous photolysis. In addition, we investigate the use of [ReCl(CO)3(dppz-(CH3)2)]− to reduce the previously studied catalyst [NiFe2], with facile electron transfer from [ReCl(CO)3(dppz-(CH3)2)]− to form [NiFe2]−.