Cooperative 1D Triazole-Based Spin Crossover Fe^II Material With Exceptional Mechanical Resilience

Cooperative 1D Triazole-Based Spin Crossover Fe^II Material With Exceptional Mechanical Resilienc

Ligandless Palladium-Catalyzed Regioselective Direct C–H Arylation of Imidazo[1,2‑<i>a</i>]imidazole Derivatives

Herein a novel access to functionalizable 6-substituted imidazo­[1,2-<i>a</i>]­imidazole scaffolds is described. The reactivity of this heterobicyclic unit toward direct C–H arylation was studied, and conditions allowing regioselective arylation at position 3 were successfully developed. The practicability of this method is manifested by the ligandless conditions and low catalyst loading. The strategy is functional group tolerant and provides rapid access to a large variety of 3,6-di­(hetero)­arylated imidazo­[1,2-<i>a</i>]­imidazole derivatives. A second arylation at position 2 was then carried out, and a library of diversified 2,3,6-tri­(hetero)­arylated imidazo­[1,2-<i>a</i>]­imidazoles was generated in good yields. A one-pot, two-step procedure was finally developed

Optimized Local Synthetic Conditions Induce Size Reduction and Phase Purification in {[Fe(Htrz)₂(trz)](BF₄)}_<i>n</i> Spin Crossover Particles

The well-known synthesis of the two polymorphs of the {[Fe(Htrz)2(trz)](BF4)}n spin crossover coordination polymer is explored with new template-free methods that allow a control over the local synthetic conditions. A “one-pot” synthesis approach is developed, in which the solid reactants are mixed together before the addition of the solvent, which is expected to generate instantaneous supersaturation conditions favoring the nucleation of particles over their growth. In a second method, the addition of ultrasound pulses promotes the appearance of local “hot spots” that affect the local temperature and allow exploring a different region of the concentration–temperature phase diagram, leading to an increase in the phase purity of the product. These two syntheses are compared to the classical method in which the reactants are first dissolved in separate solutions before being mixed. The use of a one-pot synthesis, with or without ultrasound pulses, induces a downsizing of the particle size by a factor of 500 on their volume. The addition of ultrasound pulses allows moving from a mixture of polymorphs I and II of this compound to the pure phase I. These approaches open the way to more studies on the control over the size or phase purity in such molecular compounds, without the use of any surfactant

Ligandless Palladium-Catalyzed Regioselective Direct C–H Arylation of Imidazo[1,2‑<i>a</i>]imidazole Derivatives

Herein a novel access to functionalizable 6-substituted imidazo­[1,2-<i>a</i>]­imidazole scaffolds is described. The reactivity of this heterobicyclic unit toward direct C–H arylation was studied, and conditions allowing regioselective arylation at position 3 were successfully developed. The practicability of this method is manifested by the ligandless conditions and low catalyst loading. The strategy is functional group tolerant and provides rapid access to a large variety of 3,6-di­(hetero)­arylated imidazo­[1,2-<i>a</i>]­imidazole derivatives. A second arylation at position 2 was then carried out, and a library of diversified 2,3,6-tri­(hetero)­arylated imidazo­[1,2-<i>a</i>]­imidazoles was generated in good yields. A one-pot, two-step procedure was finally developed

Naproxen–Nicotinamide Cocrystals: Racemic and Conglomerate Structures Generated by CO₂ Antisolvent Crystallization

Cocrystallization of naproxen racemic mixture and nicotinamide was investigated in this work, using compressed CO₂ as antisolvent. A novel racemic cocrystal structure containing both enantiomers of naproxen linked to nicotinamide has been produced thanks to the CO₂ antisolvent batch crystallization process. The structure of the molecular complex and its intermolecular interactions were investigated by single-crystal X-ray diffraction and attenuated total reflectance Fourier transform infrared spectroscopy. The antisolvent feed rate was found to have a direct influence on the cocrystallization outcome. The racemic cocrystal was obtained at slow and moderate CO₂ feed rate, while very fast introduction of CO₂ resulted in the formation of a mixture of chiral cocrystals (conglomerate). Cross-seedings, thermal analysis, and temperature-resolved X-ray powder diffraction were used to probe the relationship between the different phases. In addition, all powders produced with CO₂ technology were obtained as cocrystal-pure, without significant excess of naproxen or nicotinamide homocrystals