Polymorphism of 1,3-X-adamantanes (X = Br, OH, CH₃) and the crystal plastic phase formation ability

Abstract

The polymorphism of 1,3-dimethyladamantane (13DMA), 1,3-adamantanediol (13DOHA) and 1,3-dibromoadamantane (13DBrA) has been studied by X-ray powder diffraction, density measurements and differential scanning calorimetry at normal and high-pressure.

Reversible colossal barocaloric effects near room temperature in 1-X-adamantane (X=Cl, Br) plastic crystals

“…Molecular energy minimization with the Forcite module using the Dreiding forcefield available in Materials Studio Program [20] has been used to build up a rigid body molecule. It is well-known that molecular parameters of adamantane derivatives, in particular those consisting in 1-X-or 2-X-adamantane derivatives, are virtually the same [21][22][23][24][25][26][27]. For the final structural solution, rigid molecules were placed in a randomly oriented general position and through Powder Solve using Monte-Carlo approach, both the position and orientation of molecules within the unit lattice were refined.…”

Heat capacity anomalies of the molecular crystal 1-fluoro-adamantane at low temperatures

“…Substitutions at either four of the tertiary carbons (1-) or six of the secondary carbons (2-) of adamantane give rise to the 1-X-adamantane (with C 3v point group symmetry) or 2-X-adamantane derivatives (with C s symmetry). All 1-X- and 2-X-adamantane species display rich polymorphism and a large number of experimental and theoretical investigations have been devoted to their study 5 – 9 . A common characteristic of 1-X- and 2-X-adamantane derivatives is that they form orientationally disordered (OD) crystals, in which translationally ordered molecules perform reorientational jumps over well-defined orientations 4 , 10 – 12 .…”

Ultrasonic study of 1-X adamantane (X = F, Cl, Br) compounds at high pressure and at order–disorder transitions

“…Moreover, there are attempts to introduce a quantitative criterion for various adamantane derivatives in addition to molecular weight. Such a criterion was previously proposed in the work 43 – the coefficient of globularity or asphericity. The monotonic change in the globularity parameter of molecules in the 1X-adamantane series correlates well with our data on bulk moduli.…”