• Bulletin of the Korean Chemical Society
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• 제25권12호
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• pp.1911-1916
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• 2004

The conformational preference of tetrahomodioxacalix[4]arenes with three different para substituents on the phenolic ring has been investigated by using ab initio molecular orbital theory (RHF/6-31$G^{\ast}$) and density functional theory (B3LYP/6-31$G^{\ast}$). The stability order is predicted to be cone > C-1,2-alternate > partial cone > 1,3-alternate > COC-1,2-alternate. The distorted cone conformation is found to be most stable in a gas phase and the calculated results are in agreement with the reported $^1$H NMR and X-ray experimental observations. The substitution of methylene with dimethyleneoxa bridges increases the size of the annulus of the molecule, its conformational mobility, and the number of hydrogen bonding patterns. The thermodynamic stability and the conformational characteristics of tetrahomodioxacalix[4]arenes are discussed in regards of the number of phenolic hydrogen bonding patterns and the polarity of a molecule. The substituent effects on the para position of the phenolic ring are also introduced.

• Bulletin of the Korean Chemical Society
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• 제18권6호
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• pp.636-640
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• 1997

The structure and conformational behavior of the oxyanions of calix[4]arene have been studied by the NMR spectrum. The structure of the oxyanions of calix[4]arene was completely dependent upon the counter cation in present. All of the anions derived from in the presence of NaH and KH appear to exist as a cone conformation, whereas those produced with lithium cation such as n-butyllithium and LiOD show a more varied conformational behavior. The mono and tetraanions with lithium cation exist as a cone conformation, the trianions appear to exist as a partial cone conformation, and the dianions appear to disproportionate to the mono and trianions. The conformational stability decreases in the order of $Li^+$ oxyanion > $Na^+$ oxyanion > $K^+$ oxyanion.

• Bulletin of the Korean Chemical Society
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• 제35권12호
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• pp.3514-3520
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• 2014

Molecular structures of the various conformers of para-bromocalix[4]aryl derivatives 1-4 were optimized using the DFT B3LYP calculation method. The total electronic and Gibbs free energies and normal vibrational frequencies of the different structures (CONE, partial cone (PACO), 1,2-Alternate(1,2-A) and 1,3-Alternate(1,3-A)) were calculated from the four kinds of para-bromocalix[4]aryl derivatives. The B3LYP/6-31G(d,p) calculations suggested the following: 1(PACO) is the most stable among four conformers of 1; 2(CONE) is the most stable among five conformers of 2; 3(PACO) is the most stable among four conformers of 3; 4(1,3-A) is the most stable among four conformers of 4. All the most stable structures optimized by the B3LYP calculation method were in accordance with the experimental crystal structures of 1-4. The calculated IR spectra of the various conformers (CONE, PACO, 1,2-A and 1,3-A) of 1-4 were compared.

• Bulletin of the Korean Chemical Society
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• 제32권1호
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• pp.100-104
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• 2011

The structures of the conformers for 1,3-di-t-butyl-2,4-dinitro-tetramethoxysulfonylcalix[4]arene (1) and 1,2-di-t-butyl-3,4-dinitro-tetramethoxysulfonylcalix[4]arene (2) were optimized using DFT BLYP and mPW1PW91/6-31G(d,p) (hybrid HF-DF) calculation methods. We have analyzed the total electronic and Gibbs free energies and the differences between the various conformations (cone, partial-cone (PC), 1,2-alternate, and 1,3-alternate) of 1 and 2. For both compounds, the 1,3-alternate (1,3-A) conformers were calculated to be the most stable, which correlate very well with the experimental results. The orderings of the relative stability of 1 and 2 that resulted from the mPW1PW91/6-31G(d,p) calculations are the following: 1: 1,3-A (syn) > PC (syn) > PC (anti) > 1,2-A (anti) > CONE (syn); 2: 1,3-A (anti) > PC (anti) > PC (syn) > 1,2-A (anti) > 1,2-A (syn) > CONE (syn). The BLYP/6-31G(d) calculated IR spectra of the most stable 1,3-A conformers of 1 and 2 are compared.

• 대한수학회지
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• 제52권4호
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• pp.869-889
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• 2015

Let ${\Gamma}^+$ be the positive cone in a totally ordered abelian group ${\Gamma}$, and ${\alpha}$ an action of ${\Gamma}^+$ by extendible endomorphisms of a $C^*$-algebra A. Suppose I is an extendible ${\alpha}$-invariant ideal of A. We prove that the partial-isometric crossed product $\mathcal{I}:=I{\times}^{piso}_{\alpha}{\Gamma}^+$ embeds naturally as an ideal of $A{\times}^{piso}_{\alpha}{\Gamma}^+$, such that the quotient is the partial-isometric crossed product of the quotient algebra. We claim that this ideal $\mathcal{I}$ together with the kernel of a natural homomorphism $\phi:A{\times}^{piso}_{\alpha}{\Gamma}^+{\rightarrow}A{\times}^{iso}_{\alpha}{\Gamma}^+$ gives a composition series of ideals of $A{\times}^{piso}_{\alpha}{\Gamma}^+$ studied by Lindiarni and Raeburn.

• 한국결정학회지
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• 제4권1호
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• pp.25-35
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• 1993

Tetra-tert-butyl-tetrapropionyloxycalix (4) arena (C,6H,20s)의 분자 및 결정구조를 X-선 회절법으로 연구하였다. 이 결정은 삼사정계이고 공간군은 P1이다. 단위세포 길이는 a=13.664(5), b=17.585(5), c= 12.863(2)A이며 a=109.33(2), B=111.97(2), r=76.45(3) ˚, Z=2이다. 회절반점들의 세기는 흑연단색화 장치가 있는 Enraf-Nonius CAD-4 Diffractometer로 얻었으며, Mo-Ka X-선(A=0.7107A )을 사용하였다. 분자구조는 직접법으로 풀었으며 최소자 승법으로 정밀화하였다. 최종 신뢰도 R값은 2561개의 회절반점에 대하여 0.084이었다. 본 Calixarene은 partial cone conformation을 가져서 세개의 tort-butylphenyl group들과 하나의 tort-butylphenyl group의 상대적인 배열이 다르다. 세개의 propionyloxy group들은 macrocycle로 된 cavity바깥 쪽을 향하여 배열되어 있다.

• 한국결정학회지
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• 제6권2호
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• pp.80-87
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• 1995

Tetrapropionyloxycalix[4]arene(C40H40O8)의 결정 및 분자를 X-선 회절법으로 연구하였다. 이 결정은 단사정계이고 공간군은 P21/n이다. 단위세포 길이는 a=13.921(3), b=13.552(2), c=19.840(5)Å이며, β=110.38(2)°, Z=4이다. 회절반점들의 세기는 흑연단색화 장치가 있는 Enraf-Nonius CAD-4 Diffractometer로 얻었으며, Mo-Kα X-선(λ=0.7107Å)을 사용하였다. 분자구조는 직접법으로 풀었으며 최소자승법으로 정밀화하였다. 최종 신뢰도 R값은 2514개의 회절반점에 대하여 0.06이었다. 본 Calixarene은 partial cone conformation을 이루고 있어 세 개의 phenyl group들과 나머지 한 개의 phenyl group사이에 서로 다른 배향을 가지고 있다. 세 개의 phenyl group들은 macrocycle로 된 cavity 바깥쪽을 향하여 배열되어 있다.

• Bulletin of the Korean Chemical Society
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• 제15권12호
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• pp.1108-1112
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• 1994

25-Acetoxy-26,27,28-trimethoxycalix[4]arene was synthesized by the treatment of calix[4]arene trimethyl ether with acetyl chloride in the presence of NaH. The solution conformation was inferred as a partial cone conformation based on the $^1H$-and $^{13}C$ NMR spectra. The crystal structure has been determined by X-ray diffraction method. The crystals are monoclinic, space group $P2_1$/n, a=8.186 (1), b=17.137 (2), c=19.878 (3) ${\AA}$, ${\beta}$=95.67 (1)$^{\circ}$, Z=4, V=2774.90 ${\AA}^3$, $D_c$= 1.22 g $cm^{-3}$, $D_m$=1.23 g $cm^{-3}$. The intensity data were collected on an Enraf-Noninus CAD-4 Diffractometer with a graphite monochromated $Cu-K{\alpha}$ radiation. The structure was solved by direct method and refined by full-matrix least-squares methods to a final R value of 0.054 for 3675 observed reflections. The molecule possesses a partial cone conformation with one flattened phenyl unit, in which one anisol ring, distal to the ester ring, is inverted. The acetoxyphenyl ring is flattened.

• Bulletin of the Korean Chemical Society
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• 제17권7호
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• pp.643-647
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• 1996

1,2-Disubstituted chiral calix[4]arene "25-(3,5-dinitrobenzoyloxy)-26-methoxy-27,28-dihydroxycalix[4]arene" was synthesized by the reaction of 25-(3,5-dinitrobenzoyloxy)-calix[4]arene with methyl iodide in the presence of K2CO3. Methylation was occurred at the 26-position of calix[4]arene. The partial cone conformation and 1,2-substitution were characterized based on the 1H NMR, 13C NMR and X-ray diffraction analysis. The crystal structure has been determined by X-ray diffraction method. The crystals are orthorhombic, Pbca, a=10.652(1), b=17.687(1), c=32.247(3) Å, Z=8, V=6075.4(9) Å3, Dc=1.38gcm-3. The intensity data were collected on an Enraf-Nonius CAD-4 Diffractometer with a graphite monochromated Cu-Kα radiation. The structure was solved by direct method and refined by full-matrix least-squares methods to a final R value of 0.050 for 2368 observed reflections. The molecule is in the partial cone conformation. It has two strong intramolecular hydrogen bonds of O(1D)-H…O(1C)-H…O(1B).

• 한국가스학회지
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• 제24권4호
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• pp.25-31
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• 2020

산업용 혹은 발전용 가스터빈에 사용되는 이중 콘형 예혼합 연소기의 연소 특성을 이해하기 위하여 실험적 연구를 수행하였다. 노즐의 여러 연료 분사 방식에 대하여 NOx와 CO의 배출 특성, 화염 안정성 및 연소실 온도 분포에 대한 연소특성을 비교하였다. 주 연구 결과로는 연료홀 개수가 동일하고 연료 홀 직경이 감소하는 경우와 연료 홀면적이 동일하고 연료 홀 수가 감소되는 경우 연료의 연소용 공기층 침투가 커지기 때문에 NOx의 배출은 감소하지만 화염 안정성은 감소하게 된다. 그리고 동일 연료 홀 면적을 이용하는 분사방식에 있어서 연료 홀을 교차 변경하는 경우 연료의 평균 침투거리 증가로 NOx의 배출이 감소되며 연료 침투거리가 적은 연료가 화염을 안정화시키는 역할을 한다.