研究目的
Determination of the structural organization of the A-B system at different component ratios, specifically for 4-n-dodecyloxybenzoic acid and 4-pyridyl 4'-n-dodecyloxybenzoate, using IR spectroscopy and quantum chemical calculations.
研究成果
The system A consists of cyclic A···Acycl dimers; in the 1A:1B system, H-complexes of A···B type are formed. In the 2A:1B system, instead of stoichiometric trimers, complexes A···B and A···Acycl are formed in a 2:1 ratio. These findings are supported by IR spectroscopy, quantum chemical calculations, thermodynamic analysis, and density measurements, indicating that self-assembly processes are influenced by component ratios and can be controlled for synthesis purposes.
研究不足
The study is limited to specific compounds (4-n-alkoxybenzoic acids and pyridyl derivatives) and may not generalize to other systems. Quantum chemical calculations were performed in the gas phase, which might not fully represent condensed phase behavior. The harmonic approximation for vibrational frequencies may not accurately capture anharmonic effects, particularly for O-H stretches involved in hydrogen bonding.
1：Experimental Design and Method Selection:
The study involved recording IR spectra of individual compounds and mixtures, and performing quantum chemical calculations using DFT(B97-D)/6-311++G** level to simulate hydrogen-bonded complexes. The methodology included geometric optimization and vibrational frequency calculations to interpret experimental spectra and analyze thermodynamic characteristics of self-assembly processes.
2：Sample Selection and Data Sources:
Samples included individual 4-n-dodecyloxybenzoic acid (A) and 4-pyridyl 4'-n-dodecyloxybenzoate (B), and mixtures with molar ratios of 2A:1B and 1A:1B. These were prepared by gravimetric method, homogenized above clarification temperature, and slowly cooled to crystallization.
3：1B. These were prepared by gravimetric method, homogenized above clarification temperature, and slowly cooled to crystallization.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Equipment used: Zeiss Axioskop 40 polarization microscope with Linkam THMSE 600 temperature-controlled stage for polarization thermomicroscopy, DSC instrument 'Q100' from Intertech Corporation for differential scanning calorimetry, dilatometric method setup for density measurements, Nicolet 6700 Fourier transform infrared spectrometer for IR spectroscopy, and Gaussian09 software for quantum chemical calculations. Materials included KBr for IR sample preparation.
4：Experimental Procedures and Operational Workflow:
Mixtures were prepared and characterized for mesomorphic properties using polarization thermomicroscopy and DSC. IR spectra were recorded in the 4000–600 cm?1 range at room temperature. Quantum chemical calculations involved optimizing geometric structures and calculating vibrational frequencies for various H-complexes using DFT(B97-D)/6-311++G** method. Thermodynamic characteristics were calculated using statistical thermodynamics.
5：Data Analysis Methods:
IR spectra were interpreted by comparing experimental and theoretical frequencies, with scaling factors applied. Thermodynamic data were analyzed to assess stability and probability of self-assembly processes. Density measurements were used to confirm structural conclusions.
独家科研数据包，助您复现前沿成果，加速创新突破
获取完整内容
