Heterocyclic 3,5-disubstituted phenylpyrazoles and isoxazoles: Synthesis and mesomorphic behavior

Hsiu Ming Kuo; Shao Ling Tsai; Gene Hsiang Lee; Hwo Shuenn Sheu; Chung K. Lai

doi:10.1016/j.tet.2012.11.013

Heterocyclic 3,5-disubstituted phenylpyrazoles and isoxazoles: Synthesis and mesomorphic behavior

Hsiu Ming Kuo, Shao Ling Tsai, Gene Hsiang Lee, Hwo Shuenn Sheu, Chung K. Lai

Department of Chemistry

Research output: Contribution to journal › Article › peer-review

17 Scopus citations

Abstract

Three new series of heterocyclic pyrazoles Mpz-C_n and Epz-C _n and isoxazoles Iz-C_n were prepared, characterized, and their mesomorphic properties investigated. These heterocyclic derivatives were obtained by condensationecyclization of β-diketones with methylhydrazine, 2-hydradinoethanol or hydroxylamine in refluxing THF/ethanol. One single crystallographic structure of nonmesogenic Epz-C₄ was determined by Xřay analysis. It crystallizes in a triclinic space group P-1. An H-bond-induced structure was formed, giving a better aspect ratio required for the formation of mesophases. Both series of pyrazoles Mpz-C_n and EpZ-C_n exhibited monotropic smectic A phases, in contrast, isoxazoles Iz-C_n formed enantiotropic smectic C phases. A lack of H-bond due to a removal of hydrogen atom from pyrazolyl rings (-NH) significantly lowered the clearing temperatures of both Mpz-C_n and EpZ-C_n. These compounds have good thermal stabilities.

Original language	English
Pages (from-to)	618-626
Number of pages	9
Journal	Tetrahedron
Volume	69
Issue number	2
DOIs	https://doi.org/10.1016/j.tet.2012.11.013
State	Published - 14 Jan 2013

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10.1016/j.tet.2012.11.013

CCDC 1947515: Experimental Crystal Structure Determination
Sheu, H. (Contributor), Kuo, H. (Contributor), Lai, C. K. (Contributor), Lee, G. (Contributor) & Tsai, S. (Contributor), The Cambridge Structural Database, 14 Jan 2013
DOI: 10.5517/ccdc.csd.cc23ck24, https://doi.org/10.5517%2Fccdc.csd.cc23ck24
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title = "Heterocyclic 3,5-disubstituted phenylpyrazoles and isoxazoles: Synthesis and mesomorphic behavior",

abstract = "Three new series of heterocyclic pyrazoles Mpz-Cn and Epz-C n and isoxazoles Iz-Cn were prepared, characterized, and their mesomorphic properties investigated. These heterocyclic derivatives were obtained by condensationecyclization of β-diketones with methylhydrazine, 2-hydradinoethanol or hydroxylamine in refluxing THF/ethanol. One single crystallographic structure of nonmesogenic Epz-C4 was determined by X{\v r}ay analysis. It crystallizes in a triclinic space group P-1. An H-bond-induced structure was formed, giving a better aspect ratio required for the formation of mesophases. Both series of pyrazoles Mpz-Cn and EpZ-Cn exhibited monotropic smectic A phases, in contrast, isoxazoles Iz-Cn formed enantiotropic smectic C phases. A lack of H-bond due to a removal of hydrogen atom from pyrazolyl rings (-NH) significantly lowered the clearing temperatures of both Mpz-Cn and EpZ-Cn. These compounds have good thermal stabilities.",

author = "Kuo, {Hsiu Ming} and Tsai, {Shao Ling} and Lee, {Gene Hsiang} and Sheu, {Hwo Shuenn} and Lai, {Chung K.}",

note = "Funding Information: We thank the National Science Council of Taiwan , ROC for funding ( NSC 101-2113-M-0080-002-MY2 ) in generous support of this work. ",

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AU - Kuo, Hsiu Ming

AU - Tsai, Shao Ling

AU - Lee, Gene Hsiang

AU - Sheu, Hwo Shuenn

AU - Lai, Chung K.

N1 - Funding Information: We thank the National Science Council of Taiwan , ROC for funding ( NSC 101-2113-M-0080-002-MY2 ) in generous support of this work.

PY - 2013/1/14

Y1 - 2013/1/14

N2 - Three new series of heterocyclic pyrazoles Mpz-Cn and Epz-C n and isoxazoles Iz-Cn were prepared, characterized, and their mesomorphic properties investigated. These heterocyclic derivatives were obtained by condensationecyclization of β-diketones with methylhydrazine, 2-hydradinoethanol or hydroxylamine in refluxing THF/ethanol. One single crystallographic structure of nonmesogenic Epz-C4 was determined by Xřay analysis. It crystallizes in a triclinic space group P-1. An H-bond-induced structure was formed, giving a better aspect ratio required for the formation of mesophases. Both series of pyrazoles Mpz-Cn and EpZ-Cn exhibited monotropic smectic A phases, in contrast, isoxazoles Iz-Cn formed enantiotropic smectic C phases. A lack of H-bond due to a removal of hydrogen atom from pyrazolyl rings (-NH) significantly lowered the clearing temperatures of both Mpz-Cn and EpZ-Cn. These compounds have good thermal stabilities.

AB - Three new series of heterocyclic pyrazoles Mpz-Cn and Epz-C n and isoxazoles Iz-Cn were prepared, characterized, and their mesomorphic properties investigated. These heterocyclic derivatives were obtained by condensationecyclization of β-diketones with methylhydrazine, 2-hydradinoethanol or hydroxylamine in refluxing THF/ethanol. One single crystallographic structure of nonmesogenic Epz-C4 was determined by Xřay analysis. It crystallizes in a triclinic space group P-1. An H-bond-induced structure was formed, giving a better aspect ratio required for the formation of mesophases. Both series of pyrazoles Mpz-Cn and EpZ-Cn exhibited monotropic smectic A phases, in contrast, isoxazoles Iz-Cn formed enantiotropic smectic C phases. A lack of H-bond due to a removal of hydrogen atom from pyrazolyl rings (-NH) significantly lowered the clearing temperatures of both Mpz-Cn and EpZ-Cn. These compounds have good thermal stabilities.

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U2 - 10.1016/j.tet.2012.11.013

DO - 10.1016/j.tet.2012.11.013

M3 - 期刊論文

AN - SCOPUS:84878886132

VL - 69

SP - 618

EP - 626

JO - Tetrahedron

JF - Tetrahedron

SN - 0040-4020

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ER -

Heterocyclic 3,5-disubstituted phenylpyrazoles and isoxazoles: Synthesis and mesomorphic behavior

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CCDC 1947515: Experimental Crystal Structure Determination

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