scholarly journals Nitro–Nitrito Photoisomerization of Cationic Platinum(II) Complexes in the Solid State: Reactivity in Polymorphic Crystals and Glassy State

2021 ◽  
Author(s):  
Ibuki Nakamura ◽  
Ryo Sumitani ◽  
Tomoyuki Mochida
Keyword(s):  
Solid State ◽  
Glassy State ◽  
Polymorphic Crystals

Development of the Glassy State of Benzophenone and Effect of Heating Rate from the Glassy State on Solidification

1996 ◽  
Vol 455 ◽  
Author(s):  
Paul E. Thoma ◽  
John J. Boehm
Keyword(s):  
Phase Transformation ◽  
Solid State ◽  
Cooling Rate ◽  
Heating Rate ◽  
Melting Temperature ◽  
Glassy State ◽  
Equilibrium Structure ◽  
Solidification Temperature ◽  
Additional Heating ◽  
Solid State Phase Transformation

ABSTRACTBenzophenone supercools to a glass when cooled to −100°C. In fact, it is difficult to freeze benzophenone on cooling. In this investigation, the effect of cooling rate and the minimum cooling rate to obtain benzophenone as a glass is determined. From the glassy state, the influence of heating rate on the solidification temperature of benzophenone is determined. When heated at 3°C/min., solidification starts at about −29°C. Upon additional heating, melting usually starts at about +24°C, which is 23°C lower than the solid equilibrium structure melting temperature of 47°C. Occasionally the solid that forms at about −29°C undergoes a solid state phase transformation at about +22°C, when heated at 3°C/min. If this solid state phase transformation occurs, then the solid benzophenone starts to melt at 47°C. When solid benzophenone with the equilibrium structure is cooled to −100°C, no solid state phase transformation occurs. It appears that the structure that solidifies at −29°C is metastable.

scholarly journals Affirmative polymorph generation of annulenes by using CH/O interactions

2014 ◽  
Vol 70 (a1) ◽  
pp. C543-C543
Author(s):  
Ichiro Hisaki ◽  
Norimitsu Tohnai ◽  
Mikiji Miyata
Keyword(s):  
Hydrogen Bond ◽  
Solid State ◽  
Methyl Ester ◽  
Ester Group ◽  
Strong Hydrogen Bond ◽  
Weak Hydrogen Bond ◽  
Conjugated Molecules ◽  
Pi Conjugated ◽  
Polymorphic Crystals ◽  
Benzene Rings

CH/O interaction is recognized as a weak hydrogen bond with less directionality, compared with a strong hydrogen bond such as that between carboxylic acids. Therefore, the interaction does not seem to be suitable for precise design of crystal structures. In connection with this, however, we emphasized that the CH/O interaction, particularly that provided by methyl ester group, can utilize for affirmative generation of polymorphs of cyclic pi conjugated molecules. Since functionality of solid state materials based on pi conjugated molecules is crucially affected by their molecular arrangements, polymorphs are exactly appropriate systems to reveal the superstructure-dependent properties of such the materials, and therefore, affirmative preparation of polymorphs of pi conjugated molecules is challenging. Herein, we describe formation, crystallographic characterization, and superstructure-dependent properties of polymorphs of methyl ester functionalized dehydrobenzoannulenes (DBAs), a family of cyclic conjugated molecules consisted of benzene rings and acetylene units. We synthesized five DBA derivatives 1-5 with two types of annulene cores (octadehydrodibenzo[12]annulene and octadehydrotribenzo[14]annulene cores) and different number and position of methyl ester groups (Scheme1). These derivatives exhibit two to five polymorphic crystals with physical properties strongly depending with their supramolecular structures.[1-3] We believe that the present polymorph generation is exactly provided by rotationally flexible conformations of the ester groups and versatile ways of directionally tolerant CH/O interactions of the ester groups.

Defects and Diffusion in Amorphous Alloys

MRS Bulletin ◽  
1991 ◽  
Vol 16 (11) ◽  
pp. 47-52 ◽  
Author(s):  
R.S. Averback
Keyword(s):  
Solid State ◽  
Amorphous Alloys ◽  
Amorphous Materials ◽  
Ion Beam ◽  
Glassy State ◽  
High Hardness ◽  
Atomic Transport ◽  
State Diffusion ◽  
Metastable Structure ◽  
Electrical Resistivities

Since 1959 when P. Duwez showed at Caltech that Au-Si alloys could be quenched into a glassy state, there has been much interest in elucidating the nature of these amorphous materials. Certainly part of the motivation for studying amorphous alloys derives from their potential technological value: they are characterized by high hardness, corrosion and oxidation resistance, and high magnetic permeabilites and electrical resistivities but an equally strong motivation is simply that they are interesting materials. Scientific curiosity is stimulated by such fundamental questions as: What is their structure? Can defects be defined within this structure? What are the possible mechanisms of atomic transport? In addition, amorphous alloys provide a paradigm of a dense metastable structure, and how atomic transport can take place in such systems without transforming to more stable configurations is not well understood. Yet, as materials formed by nonequilibrium processing, e.g., nanocrystals, superlattices, rapidly solidified and ion-beam-modified materials, etc., find their way into technology, this question becomes increasingly germane. Ironically, much of the renewed interest in diffusion in amorphous alloys has been stimulated by the discovery, also at Caltech, of the solid-state amorphizing reaction, where multilayers of crystalline metal films transform to amorphous alloys by solid-state diffusion, rather than vice versa.

GLASS FORMATION IN MECHANICALLY ALLOYED Fe-BASED SYSTEMS

2009 ◽  
Vol 02 (04) ◽  
pp. 147-155 ◽  
Author(s):  
C. SURYANARAYANA ◽  
SATYAJEET SHARMA
Keyword(s):  
Solid State ◽  
Mechanical Alloying ◽  
Glass Formation ◽  
Glassy State ◽  
Mechanically Alloyed ◽  
Lattice Contraction ◽  
Processing Methods ◽  
Glass Forming ◽  
State Processing ◽  
Alloy Systems

Rapid solidification processing of metallic melts has been traditionally employed to synthesize metallic glasses in several alloy systems. However, in recent years, solid-state processing methods, and more specifically, mechanical alloying, have become popular methods to synthesize glassy phases in metallic alloy systems. Although a large number of criteria have been developed to identify alloy compositions that can be solidified into the glassy state, very few attempts have been made to predict the glass-forming ability by solid-state processing methods. To evaluate if some clear criteria could be developed to predict glass formation by solid-state processing methods and to understand the mechanism of glass formation, mechanical alloying of powder blends was conducted on several Fe -based alloy systems. Three different aspects of glass formation are specifically discussed in this paper. One is the development of a criterion for identifying glass-forming systems from phase diagram features, the second is the process of mechanical crystallization (formation of a crystalline phase on continued milling of the amorphous powders obtained by mechanical alloying), and the third is the novel phenomenon of lattice contraction during amorphization. It was shown that the conditions under which a glassy phase is formed by mechanical alloying are different from the solidification methods.

Solid-state polymerization in glassy state at low temperature

1968 ◽  
Vol 23 (2) ◽  
pp. 663-669 ◽  
Author(s):  
Yoneho Tabata ◽  
Kenkichi Ishigure ◽  
Yoshio Fujita ◽  
Keichi Oshima
Keyword(s):  
Solid State ◽  
Low Temperature ◽  
Glassy State ◽  
Solid State Polymerization

2D-solid state NMR studies of ultraslow motions: phenylflips and chain motions in the glassy state

1991 ◽  
Vol 131-133 ◽  
pp. 777-780 ◽  
Author(s):  
D. Schaefer ◽  
M. Hansen ◽  
B. Blümich ◽  
H.W. Spiess
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Glassy State ◽  
Nmr Studies
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