Relationship between the two-component system 1-Br-adamantane + 1-Cl-adamantane and the high-pressure properties of the pure components

Abstract

The temperature-composition phase diagram of the two-component system 1-Bradamantane and 1-Cl-adamantane has been determined by means of thermal analysis techniques and X-ray powder diffraction from the low-temperature phase to the liquid state. The crossed isopolymorphism formalism has been applied to the two-component system to infer the normal pressure properties of the orthorhombic metastable phase of 1-Cladamantane at normal pressure. The experimental pressure-temperature phase diagrams for the involved compounds are related to the two-phase equilibria determined at normal pressure and inferences about the monotropic behavior of the aforementioned orthorhombic phase are discussed.2

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

“…Since this disorder leads to = 2 possible molecular configurations and the M phase is completely ordered, the contribution to the M → O transition entropy change due to the increase in the molecular configurations is ∆ → = −1 ln( / ) = −1 ln 2~27 J K -1 kg -1 . This value is of the order of the aforementioned total transition entropy change ∆ → ~ 21 J K -1 kg -1 [15], which indicates that there are no other significant contributions to the latter, such as the entropic contribution concerning the volume change.…”

“…Experimental details of high-resolution X-ray powder diffraction measurements can be found in Ref. [15]. 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.…”

“…In this work we open up the BC analysis to two plastic crystals derived from adamantane (C10H16): 1-bromoadamantane (C10H15Br, 1-Br-ada for short) and 1-chloroadamantane (C10H15Cl, 1-Cl-ada for short). 1-Br-ada and 1-Cl-ada are obtained via substitution of an H atom linked to a 3-coordinated carbon site by a Br or Cl atom, respectively [15]. They are widely used as precursors in the synthesis of other adamantane derivatives used in pharmaceutical industry as antiviral drugs and also for the synthesis of polymers and other materials [16,17].…”

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

“…It is worth mentioning that despite 13DOHA displays an extensive hydrogen bonding network in the low-temperature phase, it transforms to an orientationally disordered high-temperature phase, while 1-adamantane-methanol, with quite similar hydrogen bonding network does not. Worth recalling here is that the relative volume change at the transition, =1.08-1.07, is higher than that at the melting [61][62][63][64][65][66][67][68][69][70] Please do not adjust margins Please do not adjust margins…”

“…[71,72] Such result confirms the preponderance of the orientational degrees of freedom, which for plastic crystals "melt" at the solid-solid (II-I) phase transition instead of at the melting process (I to L). [70,73] In addition, it must be mentioned that both the volume change at the melting and the slope of the two-phase coexistence curve,…”