Luminescence Solvato- and Vapochromism of Alkynyl-Phosphine Copper Clusters.
The reaction of [Cu(NCMe)4][PF6] with aromatic acetylenes HC2R and triphosphine 1,1,1-tris(diphenylphosphino)methane in the presence of NEt3 results in the formation of hexanuclear Cu(I) clusters with the general formula [Cu6(C2R)4{(PPh2)3CH}2][PF6]2 (R = 4-X-C6H4 (1-5) and C5H4N (6); X = NMe2 (1), OMe (2), H (3), Ph (4), CF3 (5)). The structural motif of the complexes studied consists of a Cu6 metal core supported by two phosphine ligands and stabilized by σ- and π-coordination of the alkynyl fragments (together with coordination of pyridine nitrogen atoms in cluster 6). The solid state structures of complexes 2-6 were determined by single crystal XRD analysis. The structures of the complexes in solution were elucidated by (1)H, (31)P, (1)H-(1)H COSY NMR spectroscopy, and ESI mass spectrometry. Clusters 1-6 exhibit moderately strong phosphorescence in the solid state with quantum yields up to 17%. Complexes 1-5 were found to form solvates (acetone, acetonitrile) in the solid state. The coordination of loosely bound solvent molecules strongly affects emission characteristics and leads to solvato- and vapochromic behavior of the clusters. Thus, solvent-free and acetonitrile solvated forms of 3 demonstrate contrasting emission in orange (615 nm) and blue (475 nm) regions, respectively. The computational studies show that alkynyl-centered IL transitions mixed with those of MLCT between the Cu6 metal core and the ligand environment play a dominant role in the formation of excited states and can be considerably modulated by weakly coordinating solvent molecules leading to luminescence vapochromism.
St. Petersburg State University , Institute of Chemistry, Universitetskii pr. 26, 198504 St. Petersburg, Russia.
Ilya S
IS
Krytchankou
University of Eastern Finland , Department of Chemistry, 80101 Joensuu, Finland.
Igor O
IO
Koshevoy
St. Petersburg State University , Institute of Earth Sciences, Universitetskaya nab. 7-9, 199034 St. Petersburg, Russia.
Vladislav V
VV
Gurzhiy
St. Petersburg State University , Institute of Chemistry, Universitetskii pr. 26, 198504 St. Petersburg, Russia.|Tomsk State University , Lenina pr. 36, 634050 Tomsk, Russia.
Vladimir A
VA
Pomogaev
University of Eastern Finland , Department of Chemistry, 80101 Joensuu, Finland.
Sergey P
SP
Tunik