Crystal Structure and Phase Transition of the C–H···F–H-Bonded Supramolecular Compound with 4-Nitroanilinium Based on 18-Crown-6

Abstract

Abstract:A novel inorganic-organic hybrid supramolecular macrocyclic compound, (4-nitroanilinium) (18-crown-6)(PF 6 )(1), was synthesized and characterized by infrared spectroscopy, thermogravimetric analysis, elemental analysis, differential scanning calorimetry (DSC), and single-crystal X-ray diffraction. Crystal 1 is found to comprise 1D C-H···F-P hydrogen-bonded chains of (4-nitroanilinium + ) (18-crown-6) supramolecular cations and PF 6 − anions. DSC measurements confirm that 1 undergoes a reversible phase transition at 255 K with a hysteresis width of 6 K. A strong dielectric response is observed above 250 K at a low frequency (500 Hz), suggesting the occurrence of proton transfer in the C-H···F-P hydrogen bonds. A precise analysis on the main packing and structural differences, as well as the changes in the intermolecular interaction between the low-and high-temperature phases, reveals that C-H···F-P hydrogen bonds are the main factors affecting phase transition and dielectric behavior.

Theoretical Estimation of Important Ferroelectricity-Related Parameters for Molecular Design of Host–Guest Compounds, Substituted Anilinium Tetrafluoroborate 18-Crown-6

“…For example, a series of 4-nitroanilinium-18-crown-6-based supramolecular assemblies have been recently synthesized to realize phase transition and dielectric response but without ferroelectricity. 23,24 Here, we attempt to perform molecular design of the (sub-Ani + )(18crown-6)BF 4…”

“…Sometimes, it is not so easy to ensure realization of ferroelectric ammonium-crown ether-based host–guest compounds through simple chemical modification. For example, a series of 4-nitroanilinium-18-crown-6-based supramolecular assemblies have been recently synthesized to realize phase transition and dielectric response but without ferroelectricity. , Here, we attempt to perform molecular design of the (sub-Ani + )­(18-crown-6)­BF 4 – supramolecular assemblies by delicately modifying the substituent anilinium with more different electron-donating and electron-withdrawing groups (Figure c) to successfully realize the ferroelectricity of this series of ammonium-crown ether-based host–guest compounds. First, we take the (4-MeO-Ani + )­(18-crown-6)­BF 4 – crystal as the model system to learn its structural and symmetrical characteristics and then develop operable computational methods, which can be well used to estimate ferroelectricity-related parameters, such as spontaneous polarization, phase transition temperature, and coercive field, for this series of (sub-Ani + )­(18-crown-6)­BF 4 – compounds.…”

Nursing Students' Knowledge, Attitudes and Behaviors Towards Evidence-Based Nursing

“…Gelecekte hemşirelik mesleğinin birer üyesi olacak öğrenci hemşirelerin kanıta dayalı hemşirelik konusunda henüz klinik alanda çalışmaya başlamadan önce yapılan çalışmalardan en iyi ve en yararlı kanıt temelli çalışmaları seçmeyi öğrenmeleri ve çalışma sonuçlarını klinik uygulamanın bir parçası olarak kullanmaları önemlidir (8). Hemşirelik öğrencilerinin kanıta dayalı hemşirelikle ilgili bilgi, tutum ve davranışlarının incelendiği çalışmaların yurtdışında yapıldığı görülürken (9)(10)(11)(12)(13)(14) ülkemizde hemşirelik öğrencilerinin kanıta dayalı hemşireliğe yönelik tutumlarıyla ilgili çalışmaların yapıldığı (1,5,8,(15)(16)(17)(18), ancak öğrenci hemşirelerin kanıta dayalı hemşirelik uygulamalarına ilişkin bilgi, tutum ve davranışlarının incelendiği çalışmaların ilgili ölçek geçerlik ve güvenirlik çalışması dışında sınırlı sayıda olduğu görülmüştür (3).…”