Square spirals, dimensionality and biopolymers

AbstractThis paper illustrates the diversity and esthetic beauty of the spatial patterns produced by a class of heuristic procedures describable by a one-parameter algorithm. While the patterns may provide insight into the structures of biopolymers and other macromolecules, the main focus of this work is the demonstration of how two-dimensional order may arise from one-dimensional processes

Electronic structure of CNa and CNa2 in their electronic ground states

We have studied the electronic structure of the carbyne CNa and the carbene Na2C using ab-initio SCF, MCSCF, and CI techniques. We find that CNa has a 4Σ- ground state with the companion 2Π state being, at best, slightly bound. The carbene Na2C has a highly bent 3A2 ground state (θ = 86°) with the linear 3Σg- state approximately 8 kcal/mol higher. The similarity of the bonding in both CNa and Na2C to that found for CLi and Li2C is discussed. © 1984 American Chemical Society

Thermochemical and structural studies of gallic and ellagic acids

J.Z.D acknowledges the support funding to IQFR-CSIC (Spain) and peruvian CONCYTEC (INNÓVATE PERÚ, ECIP-1-P-030-14 Grant).Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte

Thermochemical and structural studies of gallic and ellagic acids

6 pags., 2 figs., 3 tabs., 2 schs.We report a study on the energetics and structural properties of gallic (1) and ellagic (2) acids. The experimental values of standard enthalpy of formation in solid state at 298.15 K, ΔH (cd) of 1 as (−985.0 ± 2.9 kJ·mol) and 2 as (−1377.9 ± 4.7 kJ·mol) have been determined. The vapour pressure of 1 have been measure by Knudsen effusion methodology and the derived enthalpy of sublimation, Δ H , was combined with the ΔH (cd) in order to derive its gas-phase enthalpy of formation, ΔH (1,g) = −835.7 ± 4.0 kJ·mol. Quantum chemical calculations, at DFT (M05-2X) and composite ab initio Gn (n = 3, 4) levels of theory, provided the consistency of the experimental results and a plausible estimation of ΔH (g) of 2 as (−1128.6 ± 6.4 kJ·mol), which was deduced from the isodesmic-reactions methodology.J.Z.D acknowledges the support funding to IQFR-CSIC (Spain) andperuvian CONCYTEC (INNÓVATE PERÚ, ECIP-1-P-030-14 Grant). Wewish to thank Fundação para a Ciência e Tecnologia (FCT), Lisbon,Portugal, and the European Social Fund (ESF) for their financial supportto CIQUP, University of Porto (Projects:PEst-C/QUI/UI0081/2011,FCUP-CIQ-UP-NORTE-07-0124-FEDER-000065). Carlos F.R.A.C.L.thanks for is Research Grant SFRH/BPD/77972/2011