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We report here on the self-assembly of two components, a Zn(II) porphyrin substituted with four lipophilic cytidines and a linear linker substituted with two guanosines, into a Watson-Crick hydrogen-bonded tetragonal prism. The corresponding ensemble, comprising two cofacial porphyrin macrocycles, exhibited similar supramolecular behavior as a reference cyclic tetramer previously studied by us. The establishment of strong G:C interactions in apolar chlorinated solvents was demonstrated by the chemical shift recorded for the relevant H-bonded protons. Most importantly, the hexacomponent prism assembly, when partially dissociated by the addition of the competing DMSO solvent, exhibited a slow exchange on the NMR timescale with the individual constituents, which is characteristic of kinetically stabilized discrete assemblies. Absorption, emission, and CD spectroscopy experiments revealed that the spectral features of the tetragonal prism were totally different from the ones recorded for the porphyrin and linker components, which also showed strong self-aggregation in apolar solvents. Temperature-dependent experiments, monitored by NMR and optical spectroscopy techniques, revealed remarkable thermodynamic stability for the prism assembly.

The self-assembly of two lipophilic dinucleoside molecules that have a common structure, comprising a bent “Z-shaped” central block substituted at the edges with complementary G and C nucleobases, are studied in this work by a combination of 1D and 2D NMR experiments, as well as by absorption, fluorescence and circular dichroism measurements as a function of the temperature and the concentration. Watson-Crick pairing affords cyclic tetramer G:C H-bound species that are less stable than those formed by related linear dinucleosides and that, in principle, due to the unusual monomer geometry, can establish an equilibrium between different conformations with the shape of a square and a rhomb.

The most important aspects of spectral and photophysical study of aromatic compounds in the solvents capable of forming hydrogen bonds with them are presented. A careful choice of the solvents for the solvatochromic study was emphasized, and 1-chloro-n-alkanes as non-specifically interacting solvents were used. The combination of experimental measurements and theoretical calculations was shown as very important to find out which species are present in a solution at a given electronic state and what are the changes in their concentrations and properties as a result of excitation or deactivation processes.

Excited-state (ES) hydrogen-bonding dynamics and excited-state intramolecular proton transfer (ESIPT) have been extensively implicated in many important physical, chemical and biological phenomena. These events are coupled, resulting in the superior fluorescence properties of luminous molecules. We summarize our recent works, focusing on the ES hydrogen-bonding dynamics of coumarin derivatives and the ESIPT of white lighting materials. The insights into the ultrafast hydrogen-bonding events at the ESs in this chapter are expected to uncover the link between the microstructural dynamics and fluorescence properties of the luminous molecules.

By the co-crystallization of trimesic acid, TMA, with molecules such as dimethylamine, N,N,N′,N′-tetramethylethylenediamine and methanol, it has been possible to generate hydrogen-bonded four-membered networks of TMA. The three-dimensional arrangement of the four-membered networks gives rise to channels occupied by the guest molecules. It has also been possible to generate a four-membered network by co-ordination of TMA with Co(II).