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543.6+544+546 (1) |
Analysis of different substances. Analytical control in production conditions (34) |
Physical chemistry (496) |
Inorganic chemistry (450) |
SM ISO690:2012 LOZOVAN, Vasile, KRAVTSOV, Victor, PETUHOV, Oleg, COROPCEANU, Eduard, FONARI, Marina. Thermal analysis of Cd(II) coordination polymers assembled from bridging sulfate anions and N,N'-donor Schiff base ligands. In: Central and Eastern European Conference on Thermal Analysis and Calorimetry: and 14th Mediterranean Conference on Calorimetry and Thermal Analysis, Ed. 5, 28-31 august 2017, Chişinău. Roma, Italy: Academica Greifswald, 2019, Editia 5, p. 307. ISBN 978-3-940237-59-0. |
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Central and Eastern European Conference on Thermal Analysis and Calorimetry Editia 5, 2019 |
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Conferința "Central and Eastern European Conference on Thermal Analysis and Calorimetry" 5, Chişinău, Moldova, 28-31 august 2017 | ||||||
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CZU: 543.6+544+546 | ||||||
Pag. 307-307 | ||||||
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Coordination polymers are a promising class of materials. Sulfate anions with rigid tetrahedral geometry are widely employed to prepare extended network structures. The variety and diversity exhibited by this class of compounds has been reviewed by Rao et al. [1]. To increase and adjust the metal-metal distances, we used the bridging Schiff base ligands of the N,N-donor type, 1,2- bis(pyridin-4-ylethylidene)hydrazine) (4-bpmhz) and 1,2-bis(pyridin-3-ylethylidene)hydra- zine) (3- bpmhz). Following the reaction between the CdSO4·8/3H2O salt and the mentioned lingands, two coordination polymers were obtained, 2D coordination network [{Cd(4- bpmhz)(SO4)(H2O)}·0.5H2O]n (1) and the 3D coordination grid, [Cd(3-bpmhz)(SO4)(H2O)]n (2) whose crystal structures were confirmed by single-crystal X-ray diffraction analysis. 200 400 600 800 1000 -100 -80 -60 -40 -20 0 Dm, % TG DTG DTA temperatura, oC -150 -120 -90 -60 -30 0 30 dm/dt, mg/min -20 -10 0 10 20 30 40 50 DT, oC Figure Thermal analysis curves of compound 1 (left) and 2 (right) under a flow of air with the heating rate of 10 °C min-1 The thermal decomposition of compounds begins with the loss of crystallization and coordination water molecules (Figure). For compound 1, crystallization water molecules are eliminated in the temperature range 55-95 oC, 2 %, (1.9 % calcd.), then removing a coordinated water molecules, 100-160 oC, 4.2 %, (3.8 % calcd.). The slow oxidative decomposition of the 4- bpmhz ligand starts at ~ 250 oC but a significant loss of mass is recorded in the range of 340-620 oC, 50 %, (50.3 % calcd.). The constant mass remaining stable up to 920 oC is assigned to cadmium sulfate, 43.5 %, (44 % calcd.). Compound 2 is thermally stable up 174 oC, then the removal of water molecules takes place, 175-184 oC, 5 %, (3.9 % calcd.). 3-bpmhz ligand decomposition takes place in the range 190-496 oC, 51.5 %, (51.2 % calcd.). The remaining cadmium sulphate, 43.4 %, (44.8 % calcd.) is stable up to ~ 1000 oC, then begins to decompose. |
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