%0 Thesis
%A Fatima, Mariyam
%T A systematic study of intermolecular interactions in non-covalently bound complexes by using and expanding advanced broadband rotational spectroscopy
%I University of Hamburg
%V Dissertation
%M PUBDB-2022-01316
%P 182
%D 2020
%Z Dissertation, University of Hamburg, 2020
%X The interplay between intra- and intermolecular forces, with hydrogen bonding and London dispersion interactions being among the most important ones, drives bio-molecular aggregation and recognition processes. Although London dispersion interactions were described in 1930 by Fritz London, the importance of their contribution to intra- and intermolecular interactions is still not well understood at the quantitative level. With geometrically well‐defined molecular model systems, where the interplay between dispersion and hydrogen bonding is particularly interesting, it is possible to systematically examine and quantify the London dispersion contribution to intermolecular interaction energies.The spectroscopy of the model systems in a cold environment can give spectroscopic data of these systems at low temperatures and isolated conditions, and this data can be directly compared with the results from various theoretical methods. Further, the experimental information can be taken to benchmark quantum-chemical methods and can be utilized in the development and the testing of newer theoretical methods. Rotational spectroscopy, as employed in this work, is a high resolution and highly sensitive technique, which provides accurate structural information on the different binding sites in the model systems and about the intra- and intermolecular interactions within these complexes.Within the framework of this thesis, three kinds of complexes were studied in a systematic approach, which can serve as suitable challenging systems for the theoretical description and characterization of dispersion interactions. The first explores the effect of dispersion interactions when complexes are dominated by a strong classical OH–O hydrogen bond, as studied in camphor complexes with methanol and ethanol, respectively. In the second category, the effect of dispersion interaction is explored when complexes can form either via strong, classical OH–O hydrogen bonds and weaker OH–π bonds in the same molecule, as studied in the complexes of phenyl vinyl ether with methanol, diphenyl ether with water, tert-butyl alcohol and adamantanol, and dibenzofuran with water, methanol, and tert-butyl alcohol. In the third category, the effect of dispersion interaction on molecular aggregation is investigated via complexes formed only by weak OH–π and/or CH-O hydrogen bonds as well as π-π dispersion interactions, as in the study of homodimers of three similar molecules, diphenyl ether, dibenzofuran, and fluorene, which have different structural flexibility. Through these different model systems, we aim to investigate how a preferred complex structure changes either by introducing small changes in the main molecule or the binding partner or on aggregation.The development of chirped-pulse Fourier transform microwave spectroscopy has enabled the recording of wide portions of a rotational spectrum in a time-efficient way. With the advancement in electronics, it is now possible to build microwave spectrometers in a cost-effective way. Herein, a new design of a cost-effective 18-26 GHz microwave spectrometer, based on a segmented chirped-pulse approach, is built and evaluated. This new design will help to make the powerful technique of rotational spectroscopy more widespread. 
%F PUB:(DE-HGF)11
%9 Dissertation / PhD Thesis
%U https://bib-pubdb1.desy.de/record/475303