Group contribution (GC) methods to predict thermochemical properties are eminently important process design. We present a group parametrization for the heat of formation organic molecules exhibiting chemical accuracy, maximum 1 kcal/mol (4.2 kJ/mol) difference between experiment and model values while minimizing number parameters avoiding overfitting therewith reduced predictability. Compared c...

In this study, the complexation of 2,3-dihydro-1H-phenothiazine-4(5aH)-one with 14 various cations were investigated by density functional theory. At the outset, the structures of the ligand, different cations and their derived complexes were optimized geometrically. Then, IR calculations were performed on them in order to acquire the formation enthalpy and Gibbs free energy values. The obtaine...

the complex formed as a consequence of the interaction between the electron-acceptor p-chloranilic acid and an electron donor tamoxifen citrate was employed in the assay of the drug in pure powder and tablets. chloranilic acid was found to form a charge-transfer complex in a 1:1 stoichiometric ratio, with tamoxifen citrate. the wavelength of maximum absorption for the complex was found to be 55...

Various methods have been used by different investigators t.o estimate the stability of amide to amide hydrogen bonds in aqueous solution. Schellman (1) and Kauzmann (2) have discussed the thermodynamic properties of t)he C=O--HN bond in water wit,h the use of aqueous urea solutions as a model system. From studies on heats of dilution of urea in water, Schellman concluded that this bond has an ...

Group contribution (GC) methods to predict thermochemical properties are eminently important process design. Following earlier work which presented a GC model in which, for the first time, chemical accuracy (1 kcal/mol or 4 kJ/mol) was accomplished, we here discuss classes of molecules traditional approach does not hold, i.e., many results beyond accuracy. We report new ring-strain-related para...

epoxy – polysulfide copolymers without or with low amounts of epoxy in their structure have poor mechanical properties in oxidative curing system.to strengthen the mechanical properties of polysulfide elastomer inclusion of epoxy resin (epon828) as hard segment was studied. ft-ir spectroscopy and rheometry were used to verify the formation of epoxy-polysulfide copolymer.  results obtained from ...

We report a direct determination of the thermodynamic contribution that DNA single-stranded order makes to DNA duplex formation. By using differential scanning calorimetry (DSC) and temperature-dependent UV absorbance spectroscopy, we have characterized thermodynamically the thermally induced disruption of the 13-mer duplex [d(CGCATGAGTACGC)].[d(GCGTACTCATGCG)] (henceforth called S1.S2) and its...

A complete set of nearest neighbor parameters to predict the enthalpy change of RNA secondary structure formation was derived. These parameters can be used with available free energy nearest neighbor parameters to extend the secondary structure prediction of RNA sequences to temperatures other than 37 degrees C. The parameters were tested by predicting the secondary structures of sequences with...

In this work, we model thin films of β-Ca(BH4)2 to understand how nanostructuration the material can be an effective way decrease dehydrogenation enthalpy. Two different crystallographic faces Ca(BH4)2 have been investigated (i.e., (001) and (101)), two reaction pathways considered that release hydrogen through formation CaH2 CaB6, respectively. Quantum mechanical calculations predict size redu...