New High- and Low-Temperature Phase Changes of ZIF-7: Elucidation and Prediction of the Thermodynamics of Transitions

2015 ◽  
Vol 137 (42) ◽  
pp. 13603-13611 ◽  
Author(s):  
Yi Du ◽  
Bradley Wooler ◽  
Meghan Nines ◽  
Pavel Kortunov ◽  
Charanjit S. Paur ◽  
...  
Keyword(s):  
Low Temperature ◽  
Phase Changes ◽  
Temperature Phase ◽  
Low Temperature Phase

35Cl NQR Studies of Hexachlorometallates(IV) with Organic Cations, A2 [MCl6] and A'[MCl6], M=Sn, Te, Pb and A+, A'2+ = Organic Cation

1990 ◽  
Vol 45 (3-4) ◽  
pp. 293-302 ◽  
Author(s):  
Dirk Borchers ◽  
Alarich Weiss
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Low Temperature ◽  
Resonance Line ◽  
Organic Cation ◽  
Phase Changes ◽  
Organic Cations ◽  
Temperature Phase ◽  
35Cl Nqr ◽  
Low Temperature Phase

Abstract35Cl NQR spectra of eleven hexachlorometallates (IV) A1 [MCl6] and A'[MCl6], M = Sn, Te, Pb, and A+ =ethylammonium, 4-picolinium, anilinium, triethylammonium, chinoxalinium, and piperi-dinium ions, and A'2+ = 1.3-propylenediammonium ion, have been observed as a function of tem-perature. The ethylammonium hexachlorometallates(IV) (C2H5 NH3)2 [MCl6], M = Sn, Te, show a phase transition at 128.8 K and 204 K, respectively. Both compounds yield a single resonance line in their high temperature phases. In case of the stannate this single 35Cl resonance line splits up into two lines at Tc = 128.8 K, whereas for the tellurate no 35Cl NQR signals could be found in the low temperature phase. A phase transition was also found for the 1.3-propylenediammonium hexa-chlorostannate(IV) at 287 K where the six line NQR spectrum of the low temperature phase changes into a four line spectrum. In contrast, the corresponding plumbate shows no transition. All other compounds studied contain distorted [MCl6]2- octahedra, and therefore they yield more than one 35Cl resonance line. The complexes have been investigated in the temperature range temperature where the lines fade out. In case of the hexachlorostannates(IV) with the ethylammonium, the 1.3-propylenediammonium and the triethylammonium ions, the crystal structures of the compounds are known and compared with the results of the 35Cl NQR spectroscopy.

Topological polymorphism and temperature-driven topotactic transitions of metal–organic coordination polymers

CrystEngComm ◽  
2020 ◽  
Vol 22 (38) ◽  
pp. 6295-6301
Author(s):  
Vadim A. Dubskikh ◽  
Anna A. Lysova ◽  
Denis G. Samsonenko ◽  
Danil N. Dybtsev ◽  
Vladimir P. Fedin
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Solid State ◽  
Low Temperature ◽  
High Temperature Phase ◽  
Phase Changes ◽  
Organic Ligands ◽  
Temperature Phase ◽  
Metal Organic ◽  
Low Temperature Phase

A facile crystal-to-crystal solid-state phase transition between a low-temperature phase and a high temperature phase changes the MOF topology and involves a significant rearrangement of bulky organic ligands.

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