Synthesis of New Family of Thiazoline and Thiazole Esters and Investigation of their Thermal Properties

Schneider, Juliana M. F. M.; Sales, Eric Souza; Livotto, Paolo Roberto; Schneider, Paulo H.; Merlo, Aloir A.

doi:10.5935/0103-5053.20140132

Cited by 4 publications

(3 citation statements)

References 3 publications

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“…Perfluorinated thioureas 17b and 18b presented an SmA mesophase, independent of the nature of the 5-membered heterocycle. The perfluorinated alkyl chain in both compounds is the reason of preference for a lamellar SmA behavior [25,26] by segregation effects. Interestingly, isoxazoline 17a presented a monotropic SmA mesophase, while its regioisomer 17c did not show a mesophase.…”

Section: Mesomorphic Propertiesmentioning

confidence: 96%

The use of isoxazoline and isoxazole scaffolding in the design of novel thiourea and amide liquid-crystalline compounds

Gonçalves¹,

Rosa²,

Eifler‐Lima³

et al. 2020

Beilstein J. Org. Chem.

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A series of novel thiourea and amide liquid crystals containing 5-membered isoxazoline and isoxazole rings were synthetized and the liquid crystal properties studied. Thioureas were obtained using a condensation reaction of benzoyl chlorides, arylamines and ammonium thiocyanate. The amides, on the other hand, were the byproduct of a quantitative reaction which used potassium cyanate as the starting material. Thiourea and amide derivatives were predominantly SmA mesophase inductors. A nematic mesophase was observed only for thioureas and amides containing an isoxazole ring. Additionaly, the liquid crystal behavior was also dependent on the relative position of nitrogen and oxygen atoms on the 5-membered heterocycle.

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Section: Mesomorphic Propertiesmentioning

confidence: 96%

The use of isoxazoline and isoxazole scaffolding in the design of novel thiourea and amide liquid-crystalline compounds

Gonçalves¹,

Rosa²,

Eifler‐Lima³

et al. 2020

Beilstein J. Org. Chem.

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“…They trapped the molecule in argon and nitrogen noble gases and investigated the conformational changes of the molecule by near infrared and UV lights using spectroscopic methods [2]. Thiazoline and thiazole ester compounds were synthesized and their thermal properties were studied [3]. Five new molecular complexes were successfully synthesized using thiazole-4-carboxylic acid as the ligand and, these new structures were characterized by single crystal X-ray diffraction [4].…”

Section: Introductionmentioning

confidence: 99%

Conformational Analysis of Thiazole-5-Carboxylic Acid Using DFT/Td-DFT Methods

Kuş

2020

Eskişehir Technical University Journal of Science and Technology a - Applied Sciences and Engineering

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In this work, structures of the conformers of the thiazole-5-carboxylic acid (T5CA) were studied using density functional theory (DFT) with B3LYP/6-311++G(d,p) level of approximation. From calculations of the potential energy distribution depending on the orientation of the carboxylic group (C-C-OH and O=C-OH) attached to the five-membered heterocyclic ring, four conformers were found at minimum energy. Considering that the relative energy in the most stable structure is zero. The relative energies of the other conformations were found to be about 0.14, 27.11, 29.84 kJ mol-1, respectively. It was found that the carboxylic acid group of the T5CA_3 and 4 were not planar, while T5CA_1 and T5CA_2 were planar. Stabilization and donoracceptor orbital interaction energies were calculated for all conformations and orbitals were plotted using natural bond orbital analysis (NBO) method. The excited state energies were calculated and graphed using Time-Dependent Density Functional Theory (TD-DFT) calculations. The singlet state energies were tabulated for all conformations and it was seen that the most stable form with the highest oscillator strength was at the second singlet state (S2). In addition, HOMO-LUMO energy gaps were calculated and electrostatic potential surface maps were drawn for all conformations.

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“…Compared with other azole rings, thiazoline moiety has been relatively less studied, in spite of the growing interest raised by this heterocycle as a component of many natural products and synthetic compounds displaying a wide range of biological activities [1]. In this regard, diverse synthetic protocols for thiazolines have been developed from condensations of thioamides and derivatives [2][3][4][5][6], as well as cysteine and other amino acids [7][8][9].…”

Section: Introductionmentioning

confidence: 99%