Isothermal crystallization experiments were performed on the halozeotype CZX-1 with 2D temperatureand time-resolved synchrotron X-ray diffraction (TtXRD) and differential scanning calorimetry (DSC). These crystallization experiments demonstrate that the fundamental materials property, the velocity of the phase boundary of the crystallization front, v pb , can be recovered from the Kolmogorov Johnson and Mehl and Avrami (KJMA) model of phase-boundary controlled reactions by introducing the sample volume into the KJMA rate expression. An additional corrective term is required if the sample volume of the crystallization measurement is anisotropic. The concurrent disappearance of the melt and appearance of the crystalline phase demonstrate that no intermediates exist in the crystallization pathway. The velocity of the phase boundary approaches 0 as the glass transition (T g ≈ 30°C) is approached and at about 10°below melting point (T m = 173°C). The velocity of the phase boundary reaches a maximum of 30 μm s −1 at 135°C. Single or near-single crystals are grown under conditions where the v pb is much greater than the rate of nucleation.

Crystal growth and viscous relaxation are known to be activated processes, albeit inadequately described by transition state theories. By considering a transition zone and accounting for the Kauzmann-type temperature dependence of configurational entropy we here develop transition zone theory (TZT). Entropic and enthalpic activation probabilities scale with the cooperativity of the reactant, and the attempt frequency prefactor (k B T/h) is scaled by a characteristic phonon wavelength equal to twice the lattice constant for crystal growth, and the speed of sound squared for viscous relaxation. TZT accurately describes the temperature-dependent crystal growth rates and viscosity of diverse materials over the entire temperature ranges T g to T m and T g to T c, respectively, and affords a detailed mechanistic understanding of condensed matter reactions similar to that afforded to molecular chemistry by the Eyring equation.

Crystal engineering through the use of metal-based interactions is relatively common, but this approach has not been widely used to develop highly ordered liquid-crystalline (LC) phases. Herein is presented a Pt(II)/Pt(IV) system with a highly ordered LC phase engineered to form through metal-based MX chain interactions of the type Pt(II)···Cl-Pt(IV). This LC material constitutes a molecular alloy in which a single mesophase is formed from two components, and is the first alloy to include a Pt(IV) component. The molecular alloy was characterized via differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and variable-temperature X-ray diffraction (VT XRD). The alloy properties are contrasted with complimentary analyses of the individual components. The newly synthesized tetrachloro(dialkyl 4,4′-dicarboxylate-2,2′-bipyridyl)platinum(IV) complexes (PtL n Cl4, n is the number of carbons in the alkyl chain) are themselves liquid crystalline. Structural and thermal properties of the Pt(II) analogues are presented to provide context to the behaviors of the Pt(IV) species and the alloys. Single-crystal X-ray diffraction data is presented for PtL1Cl2·CH2Cl2, PtL2Cl2, and PtL16Cl2·•2CHCl3. This study demonstrates the potential of mesophase ordering through carefully engineered metal-based interactions. The resulting alloy provides a phase for studying MX chain interactions outside of the solid state.