Self-organization is a common occurrence among molecules in nature and questions of how and why these molecules interact and come together by intermolecular forces has been under investigation by those interested in molecular recognition. Synthetic molecules able to mimic nature have become important in the area of supramolecular chemistry. Calixarenes are a group of molecules that is being investigated for their ability to self-assemble into dimeric capsules. Such capsules can be very useful for catalysis, molecular recognition and for encapsulation. The synthetic stratergies involved in the synthesis of a diureidocalix[4]arene is presented. In this case the taget molecule is a tetrapropylcalix[4]arene substituted on the upper rim with two urea groups separated by a hydrocarbon chain will be synthesized. This molecule can then be used to investigate its dimerization properties.

The molecular theory of the second light-scattering virial coefficient Bp describing the effects of interacting pairs of molecules on the depolarization ratio p of Rayleigh-scattered light is reviewed, both for interacting linear and nonlinear molecules. The molecular tensor theory of Bp for nonlinear molecules is extended for the first time to include in the scattered intensity p those contributions arising from field gradient effects and induced quadrupole moments in the molecular interactions. The expressions for contributions to Bp are evaluated numerically for the nonlinear polar molecule dimethyl ether. We have used an existing light-scattering apparatus to investigate the pressure-dependence of the depolarization ratio p for dimethyl ether, allowing Bp to be extracted. The measured value is compared with the calculated value, theory and experiment being found to agree to within 9%. This success in modelling Bp for dimethyl ether spurred us on to extend our investigation to the second Kerr-effect virial coefficient BK • The molecular-tensor theory of BK for nonlinear molecules is reviewed, and is applied in this work to dimethyl ether. The calculated BK values generally lie within the uncertainty limits of the available measured data over their full range of temperatures. We have used a recently-commissioned Kerr cell to undertake our own measurement of BK for dimethyl ether at room temperature. This value is in good agreement with the findings of our molecular model, and is in reasonable agreement with the other measured data. This thesis serves to reaffirm recent claims that comprehensive dipole-induced-dipole theories of molecular interaction effects explain the observed phenomena adequately provided one works to higher orders in the molecular tensors so that the series of contributing terms has converged to a meaningful numerical result, and provided the full symmetry of the molecules is allowed for. / Thesis (M.Sc.) - University of Natal, Pietermaritzburg, 2000.

Van der Waals molecules are complexes of two or more atoms or molecules bound by weak intermolecular forces rather than a conventional chemical bond. This thesis contains a high resolution molecular beam study of the rotational spectra of two such species, ArNO and NeNO. A new hamiltonian is presented to account for the spectra of these open-shell complexes. The theory is similar to that already known for the uncomplexed diatom, nitric oxide, but is modified to an asymmetric top form appropriate for these non-linear species. Two novel interactions require inclusion. The first models a slight quenching of the NO orbital angular momentum by the rare gas atoms. The second is a large centrifugal distortion associated with the effects of the bending motion on the projection of the electronic angular momentum on the complex's a-inertial axis. A comparatively rich, though incomplete, spectrum is obtained for ArNO. Most of the transitions that originate from the lower rotational states are assigned and fitted to within a few MHz using the modified open-shell hamiltonian. Possible sources are suggested for the origins of the small residual errors between the observed and calculated transition frequencies. A vibrationally-averaged structure is derived from the fitted molecular parameters indicating an equilibrium geometry which is quite close to a T-shape. The hyperfine structure in the spectrum which is associated with the ¹⁴ N nucleus is well fitted by the hamiltonian; however, the magnetic hyperfine parameters are significantly perturbed from the values that best fit the lambda-doubling spectrum of the uncomplexed diatom. The implications of this with respect to the nature of the rare gas-nitric oxide intermolecular interaction are discussed. Greater experimental difficulties are encountered in trying to record the radiofrequency and microwave spectrum of NeNO and so fewer transitions have been measured than for ArNO. A partial analysis yields approximate values for the structural parameters. The complex exhibits a larger deviation from the T-shaped geometry than is observed for ArNO. The spectrum also provides an estimate of the magnitude of the quenching of the orbital angular momentum. The quenching interaction is somewhat larger in the neon complex.

Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [193]-203).

Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Gallivan, Martha A.; Committee Member: Hess, Dennis; Committee Member: Lee, Jay H.; Committee Member: Li, Mo; Committee Member: Ludovice, Pete.

Thesis (MScEng (Process Engineering))--Stellenbosch University, 2008. / The general objective for this thesis is to assess the ability of cellular automata to model relatively complex processes or phenomena, in particular thermodynamic scenarios. The mass transfer in packing materials of distillation columns was selected as an example due to the sufficient level of complexity in the distillation process, and its importance in a wide range of applications. A literature survey on cellular automata that summarizes the information currently available in formal publications and the internet is included to provide a general overview on the basic theoretical principles and the application of cellular automata models in the process engineering industry. The literature study was also used to identify potential requirements for the new research project. The study objective includes the construction of a cellular automata model that is able to represent transition of solutes from the fluid on the micro-surfaces of packing materials to the by-passing vapour stream, as well as the steady-state equilibrium between evaporation and condensation. Iterated model parameters sufficient for the realistic modelling of mass transfer as a result of thermodynamic driving forces, are required to meet this objective. The model behaviour was compared and the parameters subsequently adjusted according to the behaviour that is theoretically expected from the system being simulated. Qualitative (although sometimes in a quantitative format) rather than quantitative observations and comparisons were made seeing that the model has not yet been calibrated. The model that has been developed to date is not able to simulate the individual effects of chemical and thermodynamic properties although a realistic simulation of the cumulative effect exerted by these factors, or change thereof, on a system has been achieved. The accuracy of the results that have been obtained by using iterated parameters cannot be guaranteed for scenarios that deviate too much from the systems that have already been modelled successfully. The trade-off between the ability of the model to incorporate the effect of polarization, its ability to represent separation, in particular the condensation of hydrophilic substances, for strong hydrophilic packing materials and its ability to incorporate a large number of species limits the range of scenarios that can be successfully modelled. The model is able to represent the effect of a declining driving force (difference between the component vapour pressure of the gas phase and that of the liquid phase) that is typical of a system which is allowed to reach equilibrium after an initial disturbance. The model is also able to represent an additional driving force for separation caused by the effect of intermolecular forces. The model also displays the potential ability to represent the effect of different surface structures of the packing material on the extent of separation achieved at steady state as well as the rate at which such steady state conditions have been achieved. The model must be correctly scaled to minimize inaccurate results. Although several adjustments are needed to eliminate some limitations, the model has proven itself worthy of further development due to its capability to represent the basic characteristics of mass transfer in packing materials.

Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2009. / Co-crystals are excellent materials for studying intermolecular interactions in the solid-state and can be used to further our knowledge of the balance between strong and weak intermolecular interactions. The O–H∙∙∙∙∙∙Narom synthon was chosen as the focus of this investigation of hydrogen bonding motifs. The starting materials selected all have two hydrogen bond donor and/or acceptor sites for the formation of extended networks. All molecules are also aromatic such that the influence of weaker π∙∙∙∙∙∙π interactions can be included in the study. Two 3x3 grids of related co-crystals were produced from these starting materials and are reported in this thesis as part of an ongoing investigation into a broader set of co-crystals. A part of the work describes the investigation of co-crystals prepared by the combination of related benzenediol and diazine isomers taken from a 3x3 grid. The solid-state structures of each of the six starting materials are discussed briefly to describe the nature of intermolecular interactions involved in the single component crystals. Trends in hydrogen-bonding patterns as well as the weaker interactions identified in the starting materials, can be used to recognise those in the subsequent multi-component crystals. Thirteen co-crystal compounds were obtained, of which twelve structures are novel. Each of these co-crystal structures is discussed in terms of intermolecular interactions and packing in the solid state. Hydrogen-bonding patterns and structural similarities are highlighted in related co-crystal structures as well as between co-crystals and their respective starting materials. The combination of benzenediol isomers with benzodiazine isomers yielded seven novel co-crystal structures in a second 33 grid is reported. The structure of phthalazine, which has not yet been reported, is included in addition to these co-crystals, while the structures of quinazoline and quinoxaline that were retrieved from the CSD are discussed briefly. Co-crystal structures are discussed individually, focusing on the intermolecular interactions that are significant to the structural architecture of the compound. Certain co-crystals that display structural similarities with structures of the 3x3 grid, as well as with co-crystals presented in Chapter 3, are discussed in the relevant sections. Lastly, two extended pyridyl diyne ligands that were synthesised for use in future co-crystallisation studies similar to those reported earlier are briefly highlighted. The crystal structures of the pure compounds and of a hydrate of one of the ligands were obtained and discussed briefly. To date only one of these structures has been reported in the literature.

No description available.

A study of Molecular Dynamics using computational methods and modeling provides the understanding on the interaction of the atoms, properties, structure, and motion and model phenomenon. There are numerous commercial tools available for simulation, analysis and visualization. However any particular tool does not provide all the functionalities. The main objective of this work is the development of the visualization tool customized for our research needs to view the three dimensional orientation of the atom, process the simulation results offline, able to handle large volume of data, ability to display complete frame, atomic trails, and runtime response to the researchers' query with low processing time. This thesis forms the basis for the development of such an in-house tool for analysis and display of simulation results based on Open GL and MFC. Advantages, limitations, capabilities and future aspects are also discussed. The result is the system capable of processing large amount of simulation result data in 11 minutes and query response and display in less than 1 second. / by Meha Garg. / Thesis (M.S.C.S.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

As the demand for high performance small electronic devices has increased, heat removal from these devices for space use is approaching critical limits. A heat pipe is a promising device to enhance the heat removal performance due to the phase change phenomena for space thermal management system. Even though a heat pipe has a big potential to remove the thermal energy from a high heat flux source, the heat removal performance of heat pipes cannot be predicted well since the first principle of evaporation has not been established. The purpose of this study is to establish a method to apply the evaporation model based on the statistical rate theory for engineering application including vapor-liquid-structure intermolecular effect. The evaporation model is applied to the heat pipe performance analysis through a pressure balance and an energy balance in the loop heat pipe.