Structural effect of the competition of 4-picoline and water molecules to form complexes with Be,Mg and Zn phthalocyanines |
| |
Authors: | Ryszard Kubiak Jan JanczakMa?gorzata ?led? Ewa Bukowska |
| |
Institution: | Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroc?aw, Poland |
| |
Abstract: | The BePc(4-Mepy), MgPc(4-Mepy)2 were recrystallised from wet 4-picoline and the aqua M((II) phthalocyaninato complexes, BePcH2O · (4-Mepy) (Ia), (MgPcH2O · (4-Mepy))2 (IIa) and (MgPcH2O · (4-Mepy)2) · (4-Mepy) (IIb), have been obtained. Recrystallisation of ZnPc(4-Mepy) in wet 4-picoline yields the β-ZnPc in microcrystalline form. The Ia, IIa and IIb complexes were obtained in crystalline form. The composition of the Mg complexes (IIa and IIb) depends on the crystallisation temperature. The BePcH2O · (4-Mepy) compound crystallises in the centrosymmetric space group of the triclinic system, while both Mg complexes crystallise in the P21/n space group of the monoclinic system. In all crystals the central M(II) atom (Be and Mg) is 4 + 1 coordinated, equatorially by four N-isoindole atoms of Pc macrocycle and axially by O atom of water molecule. Interaction of the central M atom of MgPc with axially ligated water molecule leads to the saucer-shape of the Pc ring and deviates the central M(II) atom from the N4-isondole plane by 0.308(2), 0.482(2) and 0.537(2) Å in Ia, IIa and IIb, respectively. The molecules in the Ia and IIa crystals are linked together by a pair of O–H?N hydrogen bonds between the H atom of water molecule and the azamethine N atom of the other Pc into a dimeric structure, and the 4-picoline molecules are linked to the (MPcH2O)2 dimeric structure. In IIb crystal the MgPcH2O molecule is linked by O–H?N hydrogen bonds with two 4-picoline molecules, while the third 4-picoline molecule interacts only by the van der Waals forces. The O–H?N hydrogen bonding system and the π–π interactions between the aromatic Pc macrocyles are the key for the molecular arrangement and stabilisation of the structure. The stability of the solid-state complexes was analysed by thermogravimetric measurements. Only the solid-state spectrum of IIa complex exhibits an intense near IR absorption band. The spectra of IIa and IIb in solution are identical, the Q band is blue shifted in O-donor solvents comparing with the spectrum in N-donor solvents. |
| |
Keywords: | Phthalocyanines Berylium Magnesium Zinc Crystal structure Thermal stability |
本文献已被 ScienceDirect 等数据库收录! |
|