A giant barocaloric effect (BCE) in a molecular material Fe3(bntrz)6(tcnset)6 (FBT) is reported, where bntrz = 4‐(benzyl)‐1,2,4‐triazole and tcnset = 1,1,3,3‐tetracyano‐2‐thioethylepropenide. The crystal structure of FBT contains a trinuclear transition metal complex that undergoes an abrupt spin‐state switching between the state in which all three FeII centers are in the high‐spin (S = 2) electronic configuration and the state in which all of them are in the low‐spin (S = 0) configuration. Despite the strongly cooperative nature of the spin transition, it proceeds with a negligible hysteresis and a large volumetric change, suggesting that FBT should be a good candidate for producing a large BCE. Powder X‐ray diffraction and calorimetry reveal that the material is highly susceptible to applied pressure, as the transition temperature spans the range from 318 at ambient pressure to 383 K at 2.6 kbar. Despite the large shift in the spin‐transition temperature, its nonhysteretic character is maintained under applied pressure. Such behavior leads to a remarkably large and reversible BCE, characterized by an isothermal entropy change of 120 J kg−1 K−1 and an adiabatic temperature change of 35 K, which are among the highest reversible values reported for any caloric material thus far.

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Three new nitrogen-rich energetic compounds, N-(5-chloro-2,4-dinitrophenyl)hydrazine (1), N-(5-chloro-2,4-dinitrophenyl) guanidine (2) and N-(5-chloro-2,4-dinitrophenyl)-4-aminopyrazole (3) prepared by the nucleophilic substitution reaction of 1,3-dichloro-4,6-dinitrobenzene with hydrazine, guanidinium carbonate and 4-aminopyrazole. The compounds were characterized by 1H NMR, 13C NMR, IR and mass spectroscopy. Only compound 2 could be prepared in a suitable crystal and molecular model was determined by X-ray analysis. Compounds were investigated by TG and DSC. Thermal degradation and thermokinetic behavior were investigated by Ozawa–Flynn–Wall and Kissinger–Akahira–Sunose techniques. Compounds were observed to be prone to exothermical thermal decomposition. HOMO and LUMO levels, theoretical formation enthalpy and electrostatic maps were calculated by Gaussian09. The detonation velocity and pressure were calculated by Kamlet–Jacobs equation. The compounds were assayed for antimicrobial properties.

Özet: Azotça zengin, yeni nesil çevre dostu 1(3-klorofenil)-1H-tetrazol maddesi sentezlenmiş ve yapısı Tek kristal X-ışını kırınımı, 1 H-NMR, Kızılötesi spektroskopisi, Diferansiyel Taramalı Kalorimetre ile karakterize edilmiştir. Crystal Explorer 17 programı kullanılarak hesaplanan 1(3-klorofenil)-1H-tetrazol kristalinin Hirshfeld yüzey analizi sonucunda moleküller arası etkileşimlerinin C ... C (% 8.6), C ... H (% 4.6), N ... H (% 19.4), N ... N (% 19.4), Cl ... H (% 12.7) ve H ... H (% 12.5) atomları arasında olduğu görülmüştür. Kütle kaybı, teorik hesaplamalar ve DSC cihazında ölçülen ısı dikkate alınarak termokinetik analizi yapıldığında maddenin ekzotermik bir tepkimeyle termal olarak bozunduğu ve en olası termal parçalanma ürünlerinin 3-klorofenil radikali ve tetrazol radikali olduğu belirlenmiştir. EXPLO5 V6.03 programı kullanılarak patlama hızı 4409 m/s, patlama basıncı 5.4 GPa ve oksijen dengesi -141.742 olarak hesaplanmıştır. Yapılan bu yeni azotça zengin enerjik madde çalışması ile maddenin kristal yoğunluğu, oksijen dengesi, erime noktası, ayrışma sıcaklığı, termokinetik analizi, patlama performansı (hız, basınç) gibi önemli fiziksel ve kimyasal özellikleri belirlenmiştir. Tasarlan yeni nesil enerjik madde çevre dostu maddelere alternatif bir enerjik madde örneği sunmaktadır. Bu sonuçlar, gelecekteki yeni nesil enerjik materyallerin tasarımında önemli bir hususu vurgulamaktadır.