Why do polymorphs form? A single crystal phase transformation from weak dipolar interactions to a sixfold phenyl embrace

CrystEngComm ◽  
2002 ◽  
Vol 4 (49) ◽  
pp. 271-276 ◽  
Author(s):  
G. Sean McGrady ◽  
Marianne Odlyha ◽  
Paul D. Prince ◽  
Jonathan W. Steed
Keyword(s):  
Phase Transformation ◽  
Single Crystal ◽  
Crystal Phase ◽  
Dipolar Interactions ◽  
Crystal Phase Transformation

Partial rotation of the isopropyl group in the solid state: single-crystal-to-single-crystal phase transformation in a carvacrol derivative

CrystEngComm ◽  
2015 ◽  
Vol 17 (39) ◽  
pp. 7482-7485 ◽  
Author(s):  
Umesh D. Pete ◽  
Amol G. Dikundwar ◽  
Vaishali M. Sharma ◽  
Shridhar P. Gejji ◽  
Ratnamala S. Bendre ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Solid State ◽  
Single Crystal ◽  
Crystal Phase ◽  
Thermal Stimulus ◽  
Isopropyl Group ◽  
Group Rotation ◽  
Crystal Phase Transformation

Isopropyl group rotation observed in a single crystal of TACH appears to be a result of the counterbalance of molecular energetics and supramolecular packing in response to the thermal stimulus.

A new polymorph of ortho-ethoxy-trans-cinnamic acid: single-to-single-crystal phase transformation and mechanism

2004 ◽  
Vol 60 (3) ◽  
pp. 300-314 ◽  
Author(s):  
Manuel A. Fernandes ◽  
Demetrius C. Levendis ◽  
F. R. Ludwig Schoening
Keyword(s):  
Phase Transition ◽  
Phase Transformation ◽  
Single Crystal ◽  
Cinnamic Acid ◽  
Crystal Phase ◽  
Conformational Transformation ◽  
Cinnamic Acid Derivative ◽  
Two Temperatures ◽  
High Temperature Polymorph ◽  
Crystal Phase Transformation

The α-polymorph of ortho-ethoxy-trans-cinnamic acid (OETCA) undergoes a reversible single-crystal-to-single-crystal phase transformation at 333 K. The new high-temperature polymorph (α′-OETCA) is stable between 333 and 393 K with three molecules in the asymmetric unit (Z′ = 3), space group P\bar 1. Unlike the other polymorphs (and solvate) of OETCA recently reported, two of the molecules in α′-OETCA deviate significantly from planarity. This conformational change results in the corrugated sheet-type structure of α′-OETCA. The sheets are made up of ribbons, each composed of R_2 ^2 (8) hydrogen-bonded pairs (via the —COOH groups), which are further connected by CH...O interactions. When exposed to UV radiation the α′-OETCA polymorph can be stabilized below 333 K with ca 8% of the monomer converted into the photodimer. The crystal structures of α′-OETCA are reported at two temperatures above the phase transition point (at 345 and 375 K) as well as the stabilized forms at 173 and 293 K. A mechanism for the phase transition involving a cooperative conformational transformation coupled with a shift of layers of OETCA molecules is proposed. The α′-OETCA polymorph is also an example of a cinnamic acid derivative where two different potentially photoreactive environments exist in one crystal in which each unit cell has two non-centrosymmetric predimer sites and one centrosymmetric predimer site.

Heteropolynuclear Metamagnet Showing Spin Canting and Single-Crystal to Single-Crystal Phase Transformation

2007 ◽  
Vol 19 (9) ◽  
pp. 2162-2167 ◽  
Author(s):  
Pang-Kuan Chen ◽  
Yun-Xia Che ◽  
Ji-Min Zheng ◽  
Stuart R. Batten
Keyword(s):  
Phase Transformation ◽  
Single Crystal ◽  
Crystal Phase ◽  
Spin Canting ◽  
Crystal Phase Transformation

scholarly journals Reversible single-crystal to single-crystal phase transformation between a new Werner clathrate and its apohost

2021 ◽  
Author(s):  
Catiúcia R. M. O. Matos ◽  
Rana Sanii ◽  
Shi-Qiang Wang ◽  
Célia M. Ronconi ◽  
Michael J. Zaworotko
Keyword(s):  
Phase Transformation ◽  
Single Crystal ◽  
Crystal Phase ◽  
Reversible Transformation ◽  
Werner Clathrate ◽  
Crystal Phase Transformation

A new Werner complex exhibits reversible transformation between apohost and host–guest phase induced by nitrobenzene.

Reversibility and mechanism in a single‐crystal phase transformation

1981 ◽  
Vol 75 (2) ◽  
pp. 859-864 ◽  
Author(s):  
L. J. Soltzberg ◽  
Susan M. Cannon ◽  
Yon Won Ho ◽  
Ellen C. Armstrong ◽  
Sophie J. Bobrowski
Keyword(s):  
Phase Transformation ◽  
Single Crystal ◽  
Crystal Phase ◽  
Crystal Phase Transformation

scholarly journals NIR-Triggered Crystal Phase Transformation of NiTi-Layered Double Hydroxides Films for Localized Chemothermal Tumor Therapy

2018 ◽  
Vol 5 (4) ◽  
pp. 1700782 ◽  
Author(s):  
Donghui Wang ◽  
Naijian Ge ◽  
Tingting Yang ◽  
Feng Peng ◽  
Yuqin Qiao ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Layered Double Hydroxides ◽  
Tumor Therapy ◽  
Crystal Phase ◽  
Double Hydroxides ◽  
Crystal Phase Transformation

Reversible Luminescent Switching in an Organic Cocrystal: Multi‐Stimuli‐Induced Crystal‐to‐Crystal Phase Transformation

2020 ◽  
Vol 59 (35) ◽  
pp. 15098-15103 ◽  
Author(s):  
Yingjie Liu ◽  
Aisen Li ◽  
Shuping Xu ◽  
Weiqing Xu ◽  
Yu Liu ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Crystal Phase ◽  
Crystal Phase Transformation
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