| Autor: |
Béres KA; Research Centre for Natural Sciences, Magyar Tudósok Krt 2, 1117 Budapest, Hungary., Sajó IE; Szentagothai Research Centre, Environmental Analytical and Geoanalytical Research Group, University of Pécs, Ifjúság Útja 20, 7624 Pécs, Hungary., Lendvay G; Research Centre for Natural Sciences, Magyar Tudósok Krt 2, 1117 Budapest, Hungary., Trif L; Research Centre for Natural Sciences, Magyar Tudósok Krt 2, 1117 Budapest, Hungary., Petruševski VM; Faculty of Natural Sciences and Mathematics, Ss. Cyryl and Methodius University, 1000 Skopje, North Macedonia., Barta-Holló B; Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovica 3, 21000 Novi Sad, Serbia., Korecz L; Research Centre for Natural Sciences, Magyar Tudósok Krt 2, 1117 Budapest, Hungary., Franguelli FP; Research Centre for Natural Sciences, Magyar Tudósok Krt 2, 1117 Budapest, Hungary.; Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Műegyetem Rakpart 3, 1111 Budapest, Hungary., László K; Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, Műegyetem Rakpart 3, 1111 Budapest, Hungary., Szilágyi IM; Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Műegyetem Rakpart 3, 1111 Budapest, Hungary., Kótai L; Research Centre for Natural Sciences, Magyar Tudósok Krt 2, 1117 Budapest, Hungary.; Deuton-X Ltd., Selmeci u. 89, 2030 Érd, Hungary. |
| Abstrakt: |
An aerial humidity-induced solid-phase hydrolytic transformation of the [Zn(NH 3 ) 4 ]MoO 4 @ 2H 2 O (compound 1 @ 2H 2 O) with the formation of [(NH 4 ) x H (1- x ) Zn(OH)(MoO 4 )] n (x = 0.92-0.94) coordination polymer (formally NH 4 Zn(OH)MoO 4 , compound 2 ) is described. Based on the isostructural relationship, the powder XRD indicates that the crystal lattice of compound 1@ 2H 2 O contains a hydrogen-bonded network of tetraamminezinc (2+) and molybdate (2-) ions, and there are cavities (O 4 N 4 (μ-H 12 ) cube) occupied by the two water molecules, which stabilize the crystal structure. Several observations indicate that the water molecules have no fixed positions in the lattice voids; instead, the cavity provides a neighborhood similar to those in clathrates. The @ symbol in the notation is intended to emphasize that the H 2 O in this compound is enclathrated rather than being water of crystallization. Yet, signs of temperature-dependent dynamic interactions with the wall of the cages can be detected, and 1@ 2H 2 O easily releases its water content even on standing and yields compound 2 . Surprisingly, hydrolysis products of 1 were observed even in the absence of aerial humidity, which suggests a unique solid-phase quasi-intramolecular hydrolysis. A mechanism involving successive substitution of the ammonia ligands by water molecules and ammonia release is proposed. An ESR study of the Cu-doped compound 2 ( 2 #dotCu) showed that this complex consists of two different Cu 2+ (Zn 2+ ) environments in the polymeric structure. Thermal decomposition of compounds 1 and 2 results in ZnMoO 4 with similar specific surface area and morphology. The ZnMoO 4 samples prepared from compounds 1 and 2 and compound 2 in itself are active photocatalysts in the degradation of Congo Red dye. IR, Raman, and UV studies on compounds 1@ 2H 2 O and 2 are discussed in detail. |
