open access

https://hdl.handle.net/2115/50411

Systematic structural control of multichromic platinum(II)-diimine complexes ranging from ionic solid to coordination polymer

英語

2012-02-14

Royal Society of Chemistry

Dalton Transactions

41(6)

1878-1888

Reactions of a Pt(II)-diimine-based metalloligand Na2[Pt(CN)2(4,4'-dcbpy)] (4,4'-H2dcbpy = 4,4'-dicarboxy-2,2'-bipyridine) with alkaline-earth metal salts Mg(NO3)2・6H2O, CaCl2, SrCl2・6H2O, and BaBr2・2H2O in aqueous solution gave luminescent complexes formulated as [Mg(H2O)5][Pt(CN)2(4,4'-dcbpy)]・4H2O (MgPt-4・9H2O), {[Ca(H2O)3][Pt(CN)2(4,4'-dcbpy)]・3H2O}∞ (CaPt-4・6H2O), {[Sr(H2O)2][Pt(CN)2(4,4'-dcbpy)]・H2O}∞ (SrPt-4・3H2O), and {[Ba(H2O)2][Pt(CN)2(4,4'-dcbpy)]・3H2O}∞ (BaPt-4・5H2O), respectively. The crystal structures of all MPt-4 complexes were determined by X-ray crystallography. In these structures, the alkaline-earth metal ions are commonly coordinated to the carboxyl groups of the [Pt(CN)2(4,4'-dcbpy)]^[2-] metalloligand. In the case of MgPt-4・9H2O, the Mg(II) ion is bound by five water molecules and one oxygen atom of a carboxyl group to form a neutral complex molecule [Mg(H2O)5][Pt(CN)2(4,4'-dcbpy)]. In contrast, the alkaline-earth metal ion and metalloligand form two-dimensional (CaPt-4・6H2O) and three-dimensional (SrPt-4・3H2O and BaPt-4・5H2O) coordination networks, respectively. All fully hydrated complexes exhibited a strong phosphorescence from the triplet π-π* transition state. Luminescence spectroscopy revealed that MgPt-4・9H2O exhibited interesting multichromic (i.e., thermo-, mechano-, and vapochromic) luminescence, whereas CaPt-4・6H2O showed only thermochromic luminescence. The other two complexes did not exhibit any chromic behaviour. Combination analysis of powder X-ray diffraction, thermogravimetry, and IR spectroscopy suggests that the dimensionality of the coordination network contributes considerably to both the structural flexibility and luminescence properties; that is, the low-dimensional flexible coordination network formed in MPt-4 complexes with smaller alkaline-earth metal ions enables a structural rearrangement induced by thermal and mechanical stimuli and vapour adsorption, resulting in the observed multichromic behaviour.

学術雑誌論文

Accepted Manuscript

Dalton Trans., 2012, 41, 1878-1888 - Reproduced by permission of The Royal Society of Chemistry (RSC)

1477-9226