Explanation of the structure-property relationship of a given molecule is generally simple because the characteristics of the atomic groups and chemical bonds and the effects emerging from their interaction have long been known, both from theore- cal studies and numerous experimental results. In contrast, it is often difficult to analyze, estimate, and account for the structure-properties relationship in sup- molecules. The characteristics of supramolecules are governed both by the nature of the constituent molecules and by their configuration while the characteristics of the constituent molecules are usually evident as mentioned above; their configu- tions are difficult to control, predict, and accurately estimate because of insufficient knowledge regarding the intermolecular forces. Moreover, since most of the int- molecular forces constructing supramolecules are weak, the supramolecular str- ture may vary depending on various factors, such as modification of the molecular structure, auxiliaries, and experimental conditions. Thus, in order to obtain supramolecules with the desired structures and properties, theoretical investigations on the intermolecular forces and accumulation of experimental studies on the re- tionship between the supramolecular structure and properties are both important.

A wide range of ?elds within supramolecular chemistry are of current and great interest ranging from nanosciences, medicinal sciences, biosciences, and even organic sciences and this is a mature and extremely active area of research. In 1978, Lehn de?ned this chemistry as the "chemistry of molecular assemblies and of the intermolecular bond." In other words, supramolecular chemistry is noncovalent chemistry based upon covalent chemistry. On the other hand, it is well known that replacing the carbon atom of cyclic compounds can lead to dramatic changes in chemical and physical properties and the principles of homocyclic chemistry are often of limited value and may even lead to incorrect results. This is often indeed the case in supramolecular chemistry. The modern explosion of nonochemistry is highly based upon the fundamental recognition of intermolecular interactions engendered by supramolecular scientists. In this volume entitled Heterocyclic Supramolecules I, a part of the series Topics in Heterocyclic Chemistry, some selected topics in noncovalent ch- istry from the last decade are highlighted, with attention particularly focused on heterocyclic supramolecules as well as heterocycle-based nanosciences. The ?rst chapter, "Molecular Recognition with designed Heterocycles and their Lanthanide Complexes" by S. Mameri, S. Shinoda, and H. Tsukube - scribes various synthetic receptors for speci?c binding of cationic anionic guests mainly in the solution states. Furthermore, special attention is directed at the heterocycle-lanthanide complexes that worked as luminescent sensory devices of biologically important anions. Thus, "rare" earth metals are making the change into "hopeful" earth metals.

Explanation of the structure-property relationship of a given molecule is generally simple because the characteristics of the atomic groups and chemical bonds and the effects emerging from their interaction have long been known, both from theore- cal studies and numerous experimental results. In contrast, it is often difficult to analyze, estimate, and account for the structure-properties relationship in sup- molecules. The characteristics of supramolecules are governed both by the nature of the constituent molecules and by their configuration while the characteristics of the constituent molecules are usually evident as mentioned above; their configu- tions are difficult to control, predict, and accurately estimate because of insufficient knowledge regarding the intermolecular forces. Moreover, since most of the int- molecular forces constructing supramolecules are weak, the supramolecular str- ture may vary depending on various factors, such as modification of the molecular structure, auxiliaries, and experimental conditions. Thus, in order to obtain supramolecules with the desired structures and properties, theoretical investigations on the intermolecular forces and accumulation of experimental studies on the re- tionship between the supramolecular structure and properties are both important.

A wide range of ?elds within supramolecular chemistry are of current and great interest ranging from nanosciences, medicinal sciences, biosciences, and even organic sciences and this is a mature and extremely active area of research. In 1978, Lehn de?ned this chemistry as the "chemistry of molecular assemblies and of the intermolecular bond." In other words, supramolecular chemistry is noncovalent chemistry based upon covalent chemistry. On the other hand, it is well known that replacing the carbon atom of cyclic compounds can lead to dramatic changes in chemical and physical properties and the principles of homocyclic chemistry are often of limited value and may even lead to incorrect results. This is often indeed the case in supramolecular chemistry. The modern explosion of nonochemistry is highly based upon the fundamental recognition of intermolecular interactions engendered by supramolecular scientists. In this volume entitled Heterocyclic Supramolecules I, a part of the series Topics in Heterocyclic Chemistry, some selected topics in noncovalent ch- istry from the last decade are highlighted, with attention particularly focused on heterocyclic supramolecules as well as heterocycle-based nanosciences. The ?rst chapter, "Molecular Recognition with designed Heterocycles and their Lanthanide Complexes" by S. Mameri, S. Shinoda, and H. Tsukube - scribes various synthetic receptors for speci?c binding of cationic anionic guests mainly in the solution states. Furthermore, special attention is directed at the heterocycle-lanthanide complexes that worked as luminescent sensory devices of biologically important anions. Thus, "rare" earth metals are making the change into "hopeful" earth metals.