Calculated molecular properties for different alkanoic acid–alkylamine complexes: A comparison with measured FTIR and Raman spectra

The molecular imprinting effect of propranolol and dibenzylamine as model templates: Binding strength and selectivity

Recent studies have shown anomalies with the most studied non-covalent molecularly imprinted polymer, the propranolol imprinted one. This imprinted polymer, like many others, binds more template than the non-imprinted control polymer, but its selectivity in template adsorption is only slightly or not at all improved by imprinting, depending on the compound compared. The reasons for this anomaly are discovered here. Simple experiments show that acid homoassociation in the prepolymerisation complex is the likely cause of the anomaly. The specific conductivity of prepolymerization mixtures at different functional monomer to template ratios follows a pattern observed in homoassociating systems. Analysis of the optimal prepolymerization mixture shows that on average two molecules of the functional monomer are complexed to the basic template, even if the template lacks any other hydrogen bonding functional group than the amino group. Molecular modeling calculations provide the structure and stability of the homoassociated prepolymerization complexes. These results lead to a plausible interpretation of the anomaly, which may not be unique for the propranolol imprinted polymer, but may affect all imprinted polymers made for basic templates by using acidic functional monomers. The analytical applications of the new imprinting model are demonstrated.

A kinetics study of the heterogeneous reaction ofn-butylamine with succinic acid using an ATR-FTIR flow reactor

Heterogeneous reaction between succinic acid thin film and gas phasen-butylamine was studied, and results show that the reaction follows Langmuir–Hinshelwood mechanism and overall kinetics is dominated by surface reaction.

Conformation and NH stretching of 1,1-dihalogenoheptan-1-amines [CH₃(CH₂)₅CX₂NH₂; X=F, Cl or Br]: halogen and solvent effects

The effects of halogen and solvent on the conformation and NH stretching of 1,1-dihalogeno-heptan-1-amines [CH3(CH2)5CX2NH2; X=F, Cl or Br] were investigated using the density functional theory method. The functional used was B3LYP employing the 6-31++G(d,p) basis set for all atoms. Computations were carried out for ten possible conformational isomers of the compounds, in the gas phase and both in a non-polar solvent (benzene) and in a polar solvent (methanol). This research work indicates that both the halogen and the medium affect conformational preference, geometrical parameters and NH vibrational frequency. The findings of this work can be useful to those systems involving changes in the conformations analogous to the compounds studied.

Vibrational spectroscopic investigation and conformational analysis of 1-heptylamine: a comparative density functional study

FT-IR and Raman spectra of 1-heptylamine (1-ha) have been recorded in the region of 4000-10 cm(-1) and 4000-50 cm(-1), respectively. The conformational analysis, optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of 1-ha (C7H17N) have been examined by means of the Becke-3-Lee-Yang-Parr (B3LYP) density functional theory (DFT) method together with the 6-31++G(d,p) basis set. Furthermore, reliable vibrational assignments have been made on the basis of potential energy distribution (PED) and the thermodynamics functions, highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO) of 1-ha have been predicted. Calculations have been carried out with the possible ten conformational isomers (TT, TG, GT, GT1, GG1, GG2, GG3, GG4, GG5, GG6; T and G denote trans and gauge) of 1-ha, both in gas phase and in solution. Solvent effects have theoretically been investigated using benzene and methanol. All results indicate that the B3LYP method provides satisfactory evidence for the prediction of vibrational frequencies and the TT isomer is the most stable form of 1-ha.

Bulk and adsorbed monolayer phase behavior of binary mixtures of undecanoic acid and undecylamine: catanionic monolayers

Differential scanning calorimetry (DSC) and X-ray powder diffraction (PXRD) have been used to determine the phase behavior of the binary mixtures of undecanoic acid (A) and undecylamine (B) in the bulk. In addition, we report DSC data that indicates very similar behavior for the solid monolayers of these materials adsorbed on the surface of graphite. The two species are found to form a series of stoichiometric complexes of the type AB, A(2)B, and A(3)B on the acid rich side of the phase diagram. Interestingly, no similar series of complexes is evident on the amine rich side. As a result of this complexation, the solid monolayers of the binary mixtures exhibit a very pronounced enhancement in stability relative to the pure adsorbates.

Templated synthesis of mesolamellar n-alkylamine borophosphates

A family of lamellar mesostructured n-alkylamine borophosphates, denoted C n A-BPO (BPO stands for inorganic borophosphate layer; n = 9-15, the number of carbon atoms in the n-alkylamine chain) has been prepared hydrothermally at 160 degrees C by using neutral n-alkylamines as templates. Those C n A-BPO compounds were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric measurements, and differential thermal analysis (TG-DTA) as well as chemical analyses. Interestingly, these compounds may form a bilayer, a monolayer, or mixed state of bilayer and monolayer structures depending on the content of n-alkylamine. Linear relationships for both bilayer and monolayer compounds were observed between the interlayer distances and the numbers of carbon atoms in the n-alkylamine chain. The thickness of the inorganic layers, the arrangement of n-alkylamine in the interlayer space, and the composition of the compounds are proposed.

Phase behavior in the system water-butylammonium decanoate-decane

The phase diagram at 298.2 and 281.2 K for the ternary system water-butylammonium decanoate-decane has been determined. An isotropic solution phase extending from the water corner to the decane corner was obtained without any macroscopic phase separation. A large two-phase region extending from the water-decane axis was also observed. In addition to these phases, an anisotropic and optically birefrigent liquid crystalline phase is formed below 290.3 K. Sound velocity, conductivity, and viscosity measurements were used successfully for studies of microstructural transitions in the isotropic solution phase. From these measurements, it was concluded that a transition from normal micelles to reverse micelles takes place while passing through a bicontinuous region.