Molecular Crystals

Molecular Crystals


crystals formed by molecules bonded by weak van der Waals’ forces or by a hydrogen bond. A stronger covalent bond acts between the atoms within molecules. The phase transformations of molecular crystals—melting, sublimation, and polymorphic transitions—usually take place without the destruction of individual molecules.

Most molecular crystals are crystals of organic compounds. Naphthalene is a typical molecular crystal. Molecular crystals are also formed by certain simple substances (H2, the halogens, N2, O2, and S8), binary compounds such as H2O, CO2, N2O4, organometallic compounds, and certain complex compounds. The crystals of polymers, and also of proteins and nucleic acids, are also molecular crystals. Crystals of solidified inert gases, in which van der Waals’ forces bond atoms rather than molecules, are a special case of molecular crystals.

Low melting points, high coefficients of thermal expansion, high compressibility, and low hardness are characteristic of typical molecular crystals. Under ordinary conditions most molecular crystals are dielectrics. Some molecular crystals, such as the organic dyes, are semiconductors.


Kitaigorodskii, A. I. Molekuliarnye kristally. Moscow, 1971.
Bokii, G. B. Kristallokhimiia. Moscow, 1971.


References in periodicals archive ?
Makoto Moriya of Shizuoka University in Japan investigated molecular crystals for this purpose.
I aim to develop new BC materials by exploiting phase transitions in non-magnetic solids whose structural and thermal properties are strongly coupled, namely ferroelectric salts, molecular crystals and hybrid materials.
Among their topics are computer simulations of charged colloids, layer-by-layer assembly on stimuli-responsive microgels, the dynamics and structure of water nanotube clusters confined to nanoporous molecular crystals, the quantum electrochemical study of benzene derivatives, possibilities and limitations of electrokinetic methods in biological interfaces, and surface characteristics and attachment behaviors of bacterial cells.
The first four chapters examine the interplay of charge (polarons) and neutral (excitons) photoexcitations in pi-conjugated polymers, oligomers, and molecular crystals in the time domain of 100 fs-2 ns.
Crystals of purines are formed by molecules and classified as molecular crystals (15).
The experiments were in the fields of superconductivity, molecular crystals, and molecular electronics and published in such respected journals as Science, Nature, and others.
Kitaigorodsky, Molecular Crystals, Nauka, Moscow (1971) (in Russian).
At first, a patchwork of "nucleation islands" peppers the gold surface as molecular crystals congeal from a gas into a solid.
All materials, including dielectrics, semiconductors and molecular crystals, react to such field oscillations with an intricate interplay between atomic-scale charge displacements (polarizations) and collective carrier motion on the nanometer scale (currents).
of the Negev) presents a comprehensive text and sourcebook on the polymorphism of molecular crystals for practitioners and advanced students in disciplines concerned with the organic solid state.
During the past 20 years, however, researchers have realized that when they make extremely tiny particles of metals, inert gases or molecular crystals, the melting point drops, sometimes by a lot.
Understanding the Nature of Intermolecular Interactions in Molecular Crystals.