title: Excited-State Deactivation of Branched Phthalocyanine Compounds.
abstract: The excited-state relaxation dynamics and chromophore interactions in two phthalocyanine compounds (bis- and trisphthalocyanines) are studied by using steady-state and femtosecond transient absorption spectral measurements, where the excited-state energy-transfer mechanism is explored. By exciting phthalocyanine compounds to their second electronically excited states and probing the subsequent relaxation dynamics, a multitude of deactivation pathways are identified. The transient absorption spectra show the relaxation pathway from the exciton state to excimer state and then back to the ground state in bisphthalocyanine (bis-Pc). In trisphthalocyanine (tris-Pc), the monomeric and dimeric subunits are excited and the excitation energy transfers from the monomeric vibrationally hot S1 state to the exciton state of a pre-associated dimer, with subsequent relaxation to the ground state through the excimer state. The theoretical calculations and steady-state spectra also show a face-to-face conformation in bis-Pc, whereas in tris-Pc, two of the three phthalocyanine branches form a pre-associated face-to-face dimeric conformation with the third one acting as a monomeric unit; this is consistent with the results of the transient absorption experiments from the perspective of molecular structure. The detailed structure-property relationships in phthalocyanine compounds is useful for exploring the function of molecular aggregates in energy migration of natural photosynthesis systems.
authors.affiliation: Beijing National Laboratory for Molecular Sciences (BNLMS) and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Bejing, 100190, China.
authors.forename: Huaning
authors.initials: H
authors.lastname: Zhu
authors.affiliation: Beijing National Laboratory for Molecular Sciences (BNLMS) and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Bejing, 100190, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.affiliation: Beijing National Laboratory for Molecular Sciences (BNLMS) and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Bejing, 100190, China.|School of Materials Science and Engineering, Jiangxi University of Science and Technology, Ganzhou, 341000, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
authors.affiliation: Beijing National Laboratory for Molecular Sciences (BNLMS) and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Bejing, 100190, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Zhou
authors.affiliation: Beijing National Laboratory for Molecular Sciences (BNLMS) and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Bejing, 100190, China.
authors.forename: Yingli
authors.initials: Y
authors.lastname: Niu
authors.affiliation: Beijing National Laboratory for Molecular Sciences (BNLMS) and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Bejing, 100190, China.
authors.forename: Xinxing
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Beijing National Laboratory for Molecular Sciences (BNLMS) and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Bejing, 100190, China. guoqj@iccas.ac.cn.
authors.forename: Qianjin
authors.initials: Q
authors.lastname: Guo
authors.affiliation: Beijing National Laboratory for Molecular Sciences (BNLMS) and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Bejing, 100190, China. g1704@iccas.ac.cn.
authors.forename: Shuangqing
authors.initials: S
authors.lastname: Wang
authors.affiliation: Beijing National Laboratory for Molecular Sciences (BNLMS) and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Bejing, 100190, China.
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Yang
authors.affiliation: Beijing National Laboratory for Molecular Sciences (BNLMS) and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Bejing, 100190, China.
authors.forename: Andong
authors.initials: A
authors.lastname: Xia
mesh_terms: D007211:Indoles / Q000737:chemistry*; D054833:Isoindoles; D015394:Molecular Structure; D013056:Spectrophotometry, Ultraviolet
chemical_list: D007211:Indoles; D054833:Isoindoles; C013647:phthalocyanine
keywords: ab initio calculations; energy transfer; molecular dynamics; phthalocyanines; time-resolved spectroscopy