PHOTOPHYSICAL OVERVIEW OF EXCITATION ENERGY TRANSFER IN ORGANIC MOLECULAR ASSEMBLIES — A ROUTE TO STUDY BIO-MOLECULAR ARRAYS —

Excitonic processes in organic molecular crystals are discussed in terms of two parameters, the crystal size and the constituent molecule size. From the luminescence and absorption spectra of a series of aromatic molecular crystals we find a systematic change in exciton energy transport as functions of the size of crystal and its constituent molecule size. Characteristic features of bulk crystals and microcrystallites are as follows. (1) In bulk crystals exciton energy transport depends on the constituent molecule size. When molecules are small, the exciton energy transport occurs by free excitons, but when molecules are large free exciton transport disappears because excitons get self-trapped. (2) In microcrystallites, exciton energy transport depends on the crystallite size. When the size is larger than a critical one, excitons travel as quantum mechanical waves but when the size is smaller than the critical one the exciton waves get confined within the crystallite. The results are independent of the chemical species of constituent molecules and thus applicable to novel molecular arrays such as biological molecular arrays.

A systematic study on volumetric interactions of cyclohexanone with various aliphatic hydrocarbons

Excess volumes of mixing, VE, for binary mixtures of eyelohexanone with n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-dodecane, n-tetradecane, and n-hexadecane at 25 °C were determined from the precise and accurate experimental density data. The sign and magnitude of VE were discussed in terms of the strength of the unlike interactions present in the binary mixtures.Excess volumes of mixing of equimolar concentration [Formula: see text] were also obtained. Attempts were made to interpret [Formula: see text] in terms of the size and polarity of the constituent molecule. The two effects could not be separated, but a good linear relation between [Formula: see text] and the solubility parameter was found.