Mechanosynthesis of Higher‐Order Cocrystals: Tuning Order, Functionality and Size in Cocrystal Design**

Abstract

The ability to rationally design and predictably construct crystalline solids has been the hallmark of crystal engineering research. To date,n umerous examples of multicomponent crystals comprising organic molecules have been reported. However,t he crystal engineering of cocrystals comprising both organic and inorganic chemical units is still poorly understood and mostly unexplored. Here,w er eport anew diverse set of higher-order cocrystals (HOCs) based on the structurally versatile-yet largely unexplored-phosph(V/ V)azane heterosynthon building block. The novel ternary and quaternary cocrystals reported are held together by synergistic and orthogonal intermolecular interactions.N otably,t he HOCs can be readily obtained either via sequential or onepot mechanochemical methods.C omputational modelling methods reveal that the HOCs are thermodynamically driven to form and that their mechanical properties strongly depend on the composition and intermolecular forces in the crystal, offering untapped potential for optimizing material properties.

NH-bridged Dimeric Phosphazanes: Inorganic Molecular Switches based on Anion Responsive Bifurcated to Trifurcated Hydrogen Bond Transitions

“…32,34,44 In addition, these species have been shown to effectively bind to small molecules (e.g., acetone, DMSO and DMF), and be versatile building blocks for the engineering for high-order ternary and quaternary multicomponent cocrystals, which further broadens the scope of their applications in supramolecular applications and crystal engineering. 28,45 Common strategies for improving the HB donor ability of urea and thioureas for their use as building block in both supramolecular chemistry and molecular machines are to increase (i) the complexity (i.e., adding extra HB functionalities, electron withdrawing groups, etc.) of the substituents (Approach 1) [46][47][48] or (ii) the number of repeating units of urea/thiourea crafted within the molecular backbone (Approach 2).…”

“…Past reports on monomeric cyclodiphosphazane receptors have shown that strong HB guest, such as halide anions, favour the exo,exo conformation, 45,71 which enables these species to act as R 2 1(8) HB donors. 29,34,44 This preference for the exo,exo (over the exo,endo) in the presence of halide HB acceptors, has also been recently highlighted during the formation of high-order multicomponent cocrystals based on monomeric P V 2N2 building blocks 45. The presence of an additional P V 2N2 provide 2 and 3 with an additional degree of freedom (i.e., OFF vs ON conformations), and could potentially provide a superior performance towards anion binding and sensing if selectively switched ON.…”

Spin in Organic Cocrystals

“…This review will summarize recent advancements in the usage of organic cocrystals for spin applications, rather than the preparation methods of organic cocrystals since several excellent reviews have been documented previously [4,20] . Besides the magnetic and multiferroic properties in binary/ternary cocrystals, other spin phenomena (spin multiplicity, mechanoresponsive spin, chiral orbit and spin‐crossover) and the mobility of spin transport are also summarized and discussed.…”

Arrangements of fluorophores in the salts of imidazole tethered anthracene derivatives with pyridinedicarboxylic acids influencing photoluminescence

“…2 Among them, the ionic cocrystals of organic salts crystallising together with one or more neutral molecules of acid or base or with one or more neutral components are known in the literature. [5][6][7][8][9][10] However, beyond their structural features, their properties have not been explored in detail. In general, pK a differences among partner conjugate acid-base molecules play a decisive role in their crystallisation in a particular form.…”