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91.
Directing the Structural Features of N2‐Phobic Nanoporous Covalent Organic Polymers for CO2 Capture and Separation 下载免费PDF全文
Dr. Hasmukh A. Patel Sang Hyun Je Dr. Joonho Park Prof. Yousung Jung Prof. Ali Coskun Prof. Cafer T. Yavuz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(3):772-780
A family of azo‐bridged covalent organic polymers (azo‐COPs) was synthesized through a catalyst‐free direct coupling of aromatic nitro and amine compounds under basic conditions. The azo‐COPs formed 3D nanoporous networks and exhibited surface areas up to 729.6 m2 g?1, with a CO2‐uptake capacity as high as 2.55 mmol g?1 at 273 K and 1 bar. Azo‐COPs showed remarkable CO2/N2 selectivities (95.6–165.2) at 298 K and 1 bar. Unlike any other porous material, CO2/N2 selectivities of azo‐COPs increase with rising temperature. It was found that azo‐COPs show less than expected affinity towards N2 gas, thus making the framework “N2‐phobic”, in relative terms. Our theoretical simulations indicate that the origin of this unusual behavior is associated with the larger entropic loss of N2 gas molecules upon their interaction with azo‐groups. The effect of fused aromatic rings on the CO2/N2 selectivity in azo‐COPs is also demonstrated. Increasing the π‐surface area resulted in an increase in the CO2‐philic nature of the framework, thus allowing us to reach a CO2/N2 selectivity value of 307.7 at 323 K and 1 bar, which is the highest value reported to date. Hence, it is possible to combine the concepts of “CO2‐philicity” and “N2‐phobicity” for efficient CO2 capture and separation. Isosteric heats of CO2 adsorption for azo‐COPs range from 24.8–32.1 kJ mol?1 at ambient pressure. Azo‐COPs are stable up to 350 °C in air and boiling water for a week. A promising cis/trans isomerization of azo‐COPs for switchable porosity is also demonstrated, making way for a gated CO2 uptake. 相似文献
92.
Erdi A. Bleda Ilhan Yavuz Zikri Altun Carl Trindle 《International journal of quantum chemistry》2013,113(8):1147-1154
We use a variant of the focal point analysis to refine estimates of the relative energies of the four low‐energy torsional conformers of glycolaldehyde. The most stable form is the cis‐cis structure which enjoys a degree of H‐bonding from hydroxyl H to carbonyl O; here dihedral angles τ1 (O?C? C? O) and τ2 (C? C? O? H) both are zero. We optimized structures in both CCSD(T)/aug‐cc‐pVDZ and aug‐cc‐pVTZ; the structures agree within 0.01 Å for bond lengths and 1.0 degrees for valence angles, but the larger basis brings the rotational constants closer to experimental values. According to our extrapolation of CCSD(T) energies evaluated in basis sets ranging to aug‐cc‐pVQZ the trans‐trans form (180°, 180°) has a relative energy of 12.6 kJ/mol. The trans‐gauche conformer (160°, ±75°) is situated at 13.9 kJ/mol and the cis‐trans form (0°, 180°) at 18.9 kJ/mol. Values are corrected for zero point vibrational energy by MP2/aug‐cc‐pVTZ frequencies. Modeling the vibrational spectra is best accomplished by MP2/aug‐cc‐pVTZ with anharmonic corrections. We compute the Watsonian parameters that define the theoretical vibrational‐rotational spectra for the four stable conformers, to assist the search for these species in the interstellar medium. Six transition states are located by G4 and CBS‐QB3 methods as well as extrapolation using energies for structures optimized in CCSD(T)/aug‐cc‐pVDZ structures. We use two isodesmic reactions with two well‐established thermochemical computational schemes G4 and CBS‐QB3 to estimate energy enthalpy and Gibbs energy of formation as well as the entropy of the gas phase system. Our extrapolated electronic energies of species appearing in the isodesmic reactions produce independent values of thermodynamic quantities consistent with G4 and CBS‐QB3. © 2013 Wiley Periodicals, Inc. 相似文献
93.
Yilmaz Yildirir Özgür Pamir Serkan Yavuz Ali Dişli 《Journal of heterocyclic chemistry》2013,50(Z1):E93-E99
In this study, we report the synthesis a series of novel 2‐[N‐(1H‐tetrazol‐5‐yl)‐6,14‐endo‐etheno‐6,7,8,14‐tetrahydrothebaine‐7α‐yl]‐5‐phenyl‐1,3,4‐oxadiazole derivatives ( 7a – e ) which have potential opioid antagonist and agonist. The substitution reaction of 6,14‐endo‐ethenotetrahydrothebaine‐7α‐carbohydrazide with corresponding benzoyl chlorides gave diacylhydrazine compounds 4a – e in good yields. The treatment of compounds 4a – e with POCl3 caused the conversion of side‐chain of compounds 5a – e into 1,3,4‐oxadiazole ring at C(7) position; thus, compounds 5a – e were obtained. Subsequently, cyanamides ( 6a – e ) were prepared from compounds 5a – e and then compounds 7a – e were synthesized by the azidation of 6a – e with NaN3. The structures of the compounds were established on the basis of their IR, 1H NMR, 13C APT, 2D‐NMR (COSY, NOESY, HMQC, HMBC) and high‐resolution mass spectral data. 相似文献
94.
In this study, some new 4,6‐dimethoxy pyrimidine derivatives were synthesized. 2‐Amino‐4,6‐dimethoxy‐5‐thiocyanatopyrimidine ( 2 ) was synthesized by a reaction of 2‐amino‐4,6‐dimethoxypyrimidine with KSCN and was converted into 2‐amino‐5‐(1H‐tetrazol‐5‐ylthio)‐4,6‐dimethoxypyrimidine ( 4 ) by treatment with NaN3 in the presence of NH4Cl in DMF. Then, 1,5‐disubstitute tetrazole compounds were obtained from 4 by the alkylation reaction. In addition, some 2‐chloro‐4,6‐dimethoxy‐5‐substitute‐pyrimidines were synthesized by the diazotization method. The structures of these compounds were established on the basis of IR, 1H NMR, APT, and HRMS spectral data and were evaluated for antibacterial activities against various bacterial strains. The results showed that some of these compounds exhibited good antibacterial activity as that of standard antibiotics Penicillin, Ampicillin, and Erythromycin. 相似文献
95.
In this paper we study the consequences of the existence of conformal and special conformal Killing vectors (CKV, SCKV) for string cloud and string fluid in the context of general relativity. The inheritance symmetries of the string cloud and string fluid are discussed. Einstein's field equations have been solved for static spherically symmetric space-time with cloud and fluid of strings source via CKV. 相似文献
96.
Ayhan Yavuz Genel Bahri Ülküseven İrfan Kızılcıklı 《Russian Journal of Inorganic Chemistry》2008,53(11):1747-1753
The thiosemicarbazone derivatives R1-C6H4-CH=N-N=(C-S-R2)-NH-R3 [R1 = H, OH; R2 = H, Ph; R3 = C2H5, C3H5] were prepared by a modified general method. The Pd(II) complexes of the thiosemicarbazone ligands LI–VI were isolated in the compositions [Pd(L)Cl2], [Pd(L)Cl] and [Pd(L)2]. The 1: 1 and 1: 2 metal complexes have non-ionic character, and the compounds were characterized by analytical data and infrared and proton resonance spectroscopy. The cis-trans and syn-anti isomers of the thiosemicarbazones were determined by means of 1H NMR, and the coordination behavior of the polydentate thiosemicarbazone ligands towards the palladium ion were discussed. 相似文献
97.
Dr. Doyun Kim Dr. Thien S. Nguyen Hyejeong Lee Bolormaa Bayarkhuu Vepa Rozyyev Dr. Jeehye Byun Prof. Sheng Li Prof. Cafer T. Yavuz 《Angewandte Chemie (International ed. in English)》2023,62(28):e202304378
Porous poly(aryl thioether)s offer stability and electronic tunability by robust sulfur-aryl conjugated architecture, but synthetic access is hindered due to limited control over the nucleophilic nature of sulfides and the air sensitivity of aromatic thiols. Here, we report a simple, one-pot, inexpensive, regioselective synthesis of highly porous poly(aryl thioether)s through polycondensation of perfluoroaromatic compounds with sodium sulfide. The unprecedented temperature-dependent para-directing formation of thioether linkages leads to a stepwise transition of the polymer extension into a network, thereby allowing fine control of the porosity and optical band gaps. The obtained porous organic polymers with ultra-microporosity (<1 nm) and sulfur as the surface functional groups show size-dependent separation of organic micropollutants and selective removal of mercury ions from water. Our findings offer easy access to poly(aryl thioether)s with accessible sulfur functionalities and higher complexity, which will help in realizing advanced synthetic designs in applications such as adsorption, (photo)catalysis, and (opto)electronics. 相似文献
98.
Nihal Kan Kaynar Hasan Tanak Songul Şahin Necmi Dege Erbil Ağar Metin Yavuz 《Crystallography Reports》2016,61(2):239-242
The crystal structure of the title compound, C14H12N2O3, was recently determined as a mixture of its neutral (OH containing) and zwitterionic (NH containing) forms, in a 0.60 (4): 0.40 (4) ratio using the X-ray determination. In this study, the title compound has been characterized by FT-IR and X-ray diffraction. The redetermination showed that the title compound has only enol (OH) form because of lack of the NH stretching vibration in FT-IR spectrum. In addition, the molecular structure and tautomerism of the title compound have been discussed. 相似文献
99.
Erkan Y Czolkos I Jesorka A Wilhelmsson LM Orwar O 《Langmuir : the ACS journal of surfaces and colloids》2007,23(10):5259-5263
We introduce a rapid, simple one-step procedure for the high-yield immobilization of cholesteryl-tetraethyleneglycol-modified oligonucleotides (chol-DNA) at hydrophobic sites made of SU-8 photoresist. Topographic structures of SU-8 were microfabricated on microscope glass coverslips sputtered with a Ti/Au layer. Upon application, chol-DNA adsorbed to the SU-8 structures from solution, leaving the surrounding gold surface free of chol-DNA. chol-DNA immobilization is complete within 15 min and yields a surface coverage in the range of 20-95 pmol/cm(2), which corresponds to a film density of 10(12)-10(13) molecules/cm(2). chol-DNA immobilization is stable and can be sustained despite rinsing, drying, dry storage for several hours, and rehydration of chips. Furthermore, complementary DNA in solution hybridizes efficiently to immobilized chol-DNA. 相似文献
100.
Yavuz Ergun 《Journal of heterocyclic chemistry》2007,44(3):539-541
A short synthesis of the hexahydropyrido[4,3‐b]carbazole derivative 8 which is important for the preparation of aspidosperma alkaloids was described. Construction of the tetracyclic structure was achieved via a short synthetic route and some new carbazolone derivatives ( 4, 5, 6 and 7 ) were synthesized. 相似文献