Solvent Selective Effect Occurs in Iodinated Adamantanone Ferroelectrics

Organic ferroelectrics, as a type of crystalline compound, are generally solution processing. However, for most crystalline compounds, the changing of solvent would not influence the crystalline phase, let alone their physical performance. Here, the solvent selective effect occurs in the iodinated adamantanone ferroelectrics. By changing the solvent with different polarities, the ferroelectric crystals can be induced in two different phases, which is unprecedented to the knowledge. More strikingly, this solvent-induced transformation could realize the physical performance optimization in the orthorhombic phase (orth-I-OA, obtained from ethanol) with a stronger second harmonic generation (SHG) response, greater piezoelectric coefficient d₃₃ of 5 pC N^-1 , and larger spontaneous polarization (P_s ) of 3.43 µC cm^-2 than those of monoclinic one (mono-I-OA, obtained from ethyl acetate). Such an intriguing phenomenon might be closely related to solvent polarity. Based on the quantitative and qualitative analyses, the similar interaction energies of these two phases suggest that their transformation could be easily realized via changing the solvent. This work provides new insights into the chemical design and performance optimization of organic ferroelectrics.

A New Hybrid Lead-Free Metal Halide Piezoelectric for Energy Harvesting and Human Motion Sensing

Hybrid organic-inorganic piezoelectrics have attracted attention due to their simple synthesis, mechanical flexibility, and designability, which have promising application potential in flexible sensing and self-powered energy harvesting devices. Although some hybrid piezoelectrics are discovered, most of their structures are limited by the perovskite-type and often contain lead. Herein, the synthesis, structure, and piezoelectric properties of a new hybrid lead-free metal halide, (BTMA)₂ CoBr₄ (BTMA = benzyltrimethylammonium) are reported. The experimental and theoretical results demonstrate that this material simply composed of [CoBr₄ ]^2- tetrahedra and BTMA⁺ cations exhibits significant piezoelectricity (d₂₂ = 5.14, d₂₅ = 12.40 pC N^-1 ), low Young's and shear moduli (4.11-17.56 GPa; 1.86-7.91 GPa). Moreover, the (BTMA)₂ CoBr₄ /PDMS (PDMS = polydimethylsiloxane) composite thin films are fabricated and optimized. The 10% (BTMA)₂ CoBr₄ /PDMS-based flexible devices show attractive performance in energy harvesting with an open-circuit voltage of 19.70 V, short-circuit current of 4.24 µA, and powder density of 11.72 µW cm^-2 , catching up with those of piezoelectric ceramic composites. Meanwhile, these film devices show excellent capability in accurately sensing human body motions, such as finger bending and tapping. This work demonstrates that (BTMA)₂ CoBr₄ and related piezoelectric lead-free halides can be promising molecular materials in modern energy and sensing applications.

Preferential intermolecular interactions in a racemic mixture of amino acid Schiff base, conformational structures in solid state, and DFT studies

In this work, we report the green synthesis of a Shiff base [N-(2-hydroxy-1-naphthylidene)-l-phenylalanine (1)] derived from an α-amino acid through an ultrasound-assisted synthesis method with excellent chemical yield in a short period of time.

X-ray and theoretical investigation of (Z)-3-(adamantan-1-yl)-1-(phenyl or 3-chlorophenyl)-S-(4-bromobenzyl)isothioureas: an exploration involving weak non-covalent interactions, chemotherapeutic activities and QM/MM binding energy

A detailed exploration of crystal packing of two adamantane-isothiourea hybrid derivatives along with a known closely related structure has been performed to delineate the effect of halogen substituents and the role of weak intermolecular interactions in their supramolecular architectures. The adamantane-isothiourea hybrid derivatives used in the present study are (Z)-3-(Adamantan-1-yl)-S-(4-bromobenzyl)-1-phenylisothiourea (1), C₂₄H₂₇BrN₂S and (Z)-3-(Adamantan-1-yl)-S-(4-bromobenzyl)-1-(3-chlorophenyl)isothiourea (2), C₂₄H₂₆BrClN₂S, characterized by X-ray crystallography. The X-ray structures revealed that the molecular conformation of 1 and 2 are different and stabilized by intramolecular C-H···N interactions. In addition, a short intramolecular H···H contact is formed in 2. The Hirshfeld surface analysis was used to delineate the nature of different intermolecular interactions and their contributions toward crystal packing. The quantitative analysis of strengths of molecular dimers existed in 1 and 2 has been performed using the PIXEL method. The electrostatic potential map clearly revealed nature and strength of σ-holes at Br and Cl atoms. The topological analysis was used to characterize the nature and the strength of various intermolecular interactions including the type I Br···Br contact. Interestingly, all the H-H bonding observed in 1 and 2 show closed-shell in nature. Further, an in-vitro antimicrobial activity studies suggest that the title compounds exhibited potent antibacterial activity against all the tested Gram-positive bacterial strains and Gram-negative Escherichia coli. Compound 2 showed marked anti-proliferative activity against MCF-7 and HeLa cell lines.Communicated by Ramaswamy H. Sarma.

Role of intermolecular interactions and conformational changes in the polymorphism and vitrification process of 2,2′′-bis-substituted para-terphenyls

Conformational diversity of 2,2′′-bis-substituted para-terphenyls leads to polymorphism and contributes to their unique vitrification abilities.

Same or different – that is the question: identification of crystal forms from crystal structure data

An analysis of the CSD with structural comparison tools shows that differentiating between polymorphism and redeterminations is not always straight forward and requires of complementary tools at the hands of an expert practitioner.

Crystal structure, physicochemical properties, Hirshfeld surface analysis and antibacterial activity assays of transition metal complexes of 6-methoxyquinoline

Five complexes with 6-methoxyquinoline have been synthesized; their structural, spectroscopic, photophysical and biological properties have been studied.

Four CuI(ett) coordination polymorphs and changes in XRD upon hydrothermal condition optimization

Four [Cu^I(ett)]_n coordination polymorphs (1-α, 1-β, 1-γ and 1-δ), based on 5-(ethylthio)-1H-tetrazole (Hett), have been prepared successfully.