Hexanuclear zinc(II) carboxylate complexes from the use of pyridine-2,6-dimethanol: Synthetic, structural and photoluminescence studies

• Published in: Polyhedron 2013-03, Vol.52, p.467-475
• Main Authors: Katsoulakou, Eugenia, Dermitzaki, Despina, Konidaris, Konstantis F., Moushi, Eleni E., Raptopoulou, Catherine P., Psycharis, Vassilis, Tasiopoulos, Anastasios J., Bekiari, Vlasoula, Manessi-Zoupa, Evy, Perlepes, Spyros P., Stamatatos, Theocharis C.
• Format: Article
• Language: English
• Subjects: Crystal structures; IR spectroscopy; Metal carboxylates; Photoluminescent zinc(II) complexes; Polynuclear zinc(II) complexes; Pyridine-2,6-dimethanol
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2012.08.049

The employment of pyridine-2,6-dimethanol (pdmH2) in zinc(II) carboxylate chemistry has afforded complexes [Zn6(OH)2(O2CR)8(pdmH)2] (R=Ph (1); But (2)) with a four edge-sharing triangular topology. The benzoate-analogue displays photoluminescence, while the pivalate-analogue shows a non-emissive character. The employment of pyridine-2,6-dimethanol (pdmH2) in zinc(II) carboxylate chemistry is reported. The syntheses, crystal structures, and spectroscopic characterization are described for the structurally similar cluster compounds [Zn6(OH)2(O2CR)8(pdmH)2] (R=Ph (1); But (2)), obtained in very good yields by the reactions between Zn(O2CR)2·2H2O (R=Ph, But) and pdmH2 in a 3:1molar ratio in MeOH or MeCN solvent media, respectively. The [Zn6(μ3-OH)2(μ3-OR)2]8+ core of both clusters can be conveniently described as four edge-sharing triangles (RO−=pdmH−). The three crystallographically unique metal ions in both 1 and 2 are found in three different coordination environments (4-, 5- and 6-coordinate), within the same molecule, a very rare case in hexanuclear Zn(II) cluster chemistry. The benzoate-analogue ZnII6 (1) displays photoluminescence with a maximum at 404nm, upon maximum excitation at 337nm, whereas the pivalate-analogue ZnII6 (2) shows a non-emissive character; the origin of the photoluminescence is discussed.