title: Reversible redox-switchable second-order optical nonlinearity in polyoxometalate: a quantum chemical study of [PW11O39(ReN)]n- (n = 3-7).
abstract: In this paper, the relationship between the reversible redox properties and the second-order nonlinear optical (NLO) responses for the title series of complexes has been systematically investigated by using the time-dependent density functional theory (TDDFT) method combined with the sum-over-states (SOS) formalism. The results reveal that the successive reduction processes of five PW11ReN redox states should be PW11ReVII (1) --> PW11ReVI (2) --> PW11ReV (3) --> PW11ReV1e ( 4) --> PW 11ReV2e (5). Furthermore, their electrochemical properties have been reproduced successfully. It is noteworthy that the second-order NLO behaviors can be switched by reversible redox for the present studied complexes. Full oxidation constitutes a convenient way to switch off the second-order polarizability (system 1). The incorporation of extra electrons causes significant enhancement in the second-order NLO activity, especially for the third reduced state (system 4), whose static second-order polarizability (betavec) is about 144 times larger than that of fully oxidized 1. The characteristic of the charge-transfer transition corresponding to the dominant contributions to the betavec values indicates that metal-centered redox processes influence the intramolecular donor or acceptor character. Therefore, these kinds of complexes with the facile and reversible redox states could become excellent switchable NLO materials.
authors.affiliation: Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun, P.R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Guan
authors.forename: Guochun
authors.initials: G
authors.lastname: Yang
authors.forename: Chunguang
authors.initials: C
authors.lastname: Liu
authors.forename: Ping
authors.initials: P
authors.lastname: Song
authors.forename: Liang
authors.initials: L
authors.lastname: Fang
authors.forename: Likai
authors.initials: L
authors.lastname: Yan
authors.forename: Zhongmin
authors.initials: Z
authors.lastname: Su
mesh_terms: D003198:Computer Simulation; D008958:Models, Molecular; D008968:Molecular Conformation; D009584:Nitrogen / Q000737:chemistry*; D055095:Optics and Photonics; D010084:Oxidation-Reduction; D010758:Phosphorus / Q000737:chemistry*; D011789:Quantum Theory; D012211:Rhenium / Q000737:chemistry*; D013816:Thermodynamics; D014414:Tungsten / Q000737:chemistry*; D017973:Tungsten Compounds / Q000737:chemistry*; D000099294:Polyoxometalates
chemical_list: D009584:Nitrogen; D010758:Phosphorus; D012211:Rhenium; D014414:Tungsten; D017973:Tungsten Compounds; C102296:polyoxometalate I; D000099294:Polyoxometalates