Premium
Photoinduced Processes within Compact Dyads Based on Triphenylpyridinium‐Functionalized Bipyridyl Complexes of Ruthenium( II )
Author(s) -
Lainé Philippe P.,
Ciofini Ilaria,
Ochsenbein Philippe,
Amouyal Edmond,
Adamo Carlo,
Bedioui Fethi
Publication year - 2005
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200401150
Subject(s) - ruthenium , redox , cyclic voltammetry , chemistry , bipyridine , electrochemistry , crystallography , photochemistry , acceptor , electronic structure , computational chemistry , electrode , catalysis , inorganic chemistry , crystal structure , organic chemistry , physics , condensed matter physics
As an alternative to conventional charge‐separation functional molecular models based on long‐range ET within redox cascades, a “compact approach” has been examined. To this end, spacer elements usually inserted between main redox‐active units within polyad systems have been removed, allowing extended rigidity but at the expense of enhanced intercomponent electronic communication. The molecular assemblies investigated here are of the P‐( θ 1 )‐A type, where the θ 1 twist angle is related to the degree of conjugation between the photosensitizer (P, of {Ru(bpy) 3 } 2+ type) and the electron‐acceptor (A). 4‐ N ‐ and 4‐ N ‐,4′‐ N ‐(2,4,6‐triphenylpyridinio)‐2,2′‐bipyridine ligands ( A 1 ‐bpy and A 2 ‐bpy , respectively) have been synthesized to give complexes with Ru II , 1‐bpy and 2‐bpy , respectively. Combined solid‐state analysis (X‐ray crystallography), solution studies ( 1 H NMR, cyclic voltammetry) and computational structural optimization allowed verifying that θ 1 angle approaches 90° within 1‐bpy and 2‐bpy in solution. Also, anticipated existence of strong intercomponent electronic coupling has been confirmed by investigating electronic absorption properties and electrochemical behavior of the compounds. The capability of 1‐bpy and 2‐bpy to undergo PET process was evaluated by carrying out their photophysical study (steady state emission and time‐resolved spectroscopy at both 293 and 77 K). The conformational dependence of photoinduced processes within P‐( θ 1 )‐A systems has been established by comparing the photophysical properties of 1‐bpy (and 2‐bpy ) with those of an affiliated species reported in the literature, 1‐phen . A complementary theoretical analysis (DFT) of the change of spin density distribution within model [ 1‐bpy ( θ 1 )] − mono‐reduced species as a function of θ 1 has been undertaken and the possibility of conformationally switching emission properties of P was derived.