PREFACE

Hydrogen bonding is of universal importance in chemistry, biology, and physics. Hydrogen bonding is central to the understanding of the microscopic structures and functions in many complex systems, for example hydrogen-bonded water or alcohols networks, organic compounds in solution, crystal engineering, self-assembled supramolecular architectures, proteins, and DNA building blocks of the life. Moreover, hydrogen bonding structures and dynamics in the excited states play also important roles on determining many chemical, physical and biochemical processes. In general, fluorescence emission behaviors of the organic and biological chromophores can be significantly influenced by the intermolecular hydrogen bonding interactions between chromophores and the protic solvents or biological surroundings. Furthermore, ultrafast deactivation processes of photoexcited molecular and supramolecular systems can be remarkably facilitated by the excited-state hydrogen bonding. In particular, the excited-state hydrogen transfer is tightly related to the excited-state hydrogen bonding structures and dynamics. Hydrogen bonding in the ground state for various types of molecular an