Towards a temperature-guided molecular switch: an unusual reversible low-temperature polymorphic phase transition in a conformationally locked environment

2009 ◽  
pp. 5981 ◽  
Author(s):  
Goverdhan Mehta ◽  
Saikat Sen
2006 ◽  
Vol 62 (1) ◽  
pp. 102-108 ◽  
Author(s):  
G. Ślósarek ◽  
M. Kozak ◽  
J. Gierszewski ◽  
A. Pietraszko

The crystal structure of kinetin dihydrogenphosphate has been determined at 115 and 293 K. Kinetin dihydrogenphosphate undergoes a polymorphic phase transition at 291.1 K. In both phases the crystal belongs to the triclinic system with the symmetry described by the space group P\bar 1. In the low-temperature phase, the unit cell is doubled along the a axis. There is a dynamic equilibrium between different tautomeric forms of the adenine residue, determined by the distribution of H atoms within the network of hydrogen bonds.


2015 ◽  
Vol 119 (5) ◽  
pp. 1787-1792 ◽  
Author(s):  
Alexey V. Markin ◽  
Evgeny Markhasin ◽  
Semen S. Sologubov ◽  
Qing Zhe Ni ◽  
Natalia N. Smirnova ◽  
...  

2004 ◽  
Vol 52 (4) ◽  
pp. 479-487 ◽  
Author(s):  
Cs. Pribenszky ◽  
M. Molnár ◽  
S. Cseh ◽  
L. Solti

Cryoinjuries are almost inevitable during the freezing of embryos. The present study examines the possibility of using high hydrostatic pressure to reduce substantially the freezing point of the embryo-holding solution, in order to preserve embryos at subzero temperatures, thus avoiding all the disadvantages of freezing. The pressure of 210 MPa lowers the phase transition temperature of water to -21°C. According to the results of this study, embryos can survive in high hydrostatic pressure environment at room temperature; the time embryos spend under pressure without significant loss in their survival could be lengthened by gradual decompression. Pressurisation at 0°C significantly reduced the survival capacity of the embryos; gradual decompression had no beneficial effect on survival at that stage. Based on the findings, the use of the phenomena is not applicable in this form, since pressure and low temperature together proved to be lethal to the embryos in these experiments. The application of hydrostatic pressure in embryo cryopreservation requires more detailed research, although the experience gained in this study can be applied usefully in different circumstances.


2003 ◽  
Vol 36 (1) ◽  
pp. 141-145 ◽  
Author(s):  
L. J. Farrugia ◽  
P. Macchi ◽  
A. Sironi

The coordination complex [Ni(en)3]2+(NO{}_{3}^{- })2(en = 1,2-diaminoethane) undergoes a sharp reversible displacive phase transition at ∼109 K, changing space group fromP6322 above the transition temperature toP6522 below. The phase change is accompanied by a tripling of thecaxis on cooling, resulting in an easy detection of the transition in images from area-detector diffractometers. The transition has been followed using a Nonius KappaCCD and a Bruker SMART APEX CCD. Data sets were collected over the temperature range 100–113 K and integrated using the low-temperature orientation matrix. Reflections withl≠ 3nshow a smooth and rapid decrease in intensity to zero on warming from 106.5 to 111 K. The results are reproducible to within ±2 K in two laboratories and suggest that this compound may be useful as a liquid-nitrogen cryo-calibrant for diffraction instruments equipped with area detectors.


1998 ◽  
Vol 327-329 ◽  
pp. 391-394
Author(s):  
Keiichi Ikegami ◽  
Shin-ichi Kuroda ◽  
Tomoyuki Akutagawa ◽  
Taro Konuma ◽  
Takayoshi Nakamura ◽  
...  

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