Dinaphthyl propane

Quenching Excimers and Exciplexes.—By measurements of decay times and fluorescence anisotropy of pyrene and the excimer in cellulose acetate films it has been found that the medium consists of spaces where small pyrene molecules have considerable freedom, Dissado and Walmsley have developed a complete theory of excimer formation and exciton-induced lattice distortion in crystals. Reference is made to data on 9-cyanoanthracene. The spectroscopy of chemically linked dimers of l,3-(l,l -dinaphthyl)propane in a... 

Information on microviscosity is obtained by studying the excimer forming capabilities of suitable fluorescent probes. The excimer, which is a complex of a ground state and excited state monomer, has a characteristic emission frequency. The intramolecular excimer formation for example, of 1,3-dinaphthyl propane (DNP), is a sensitive function of the microviscosity of its neighborhood. This property, expressed as the ratio of the excimer and monomer yield (/e//m) for DNP, has been determined for dodecyl sulfonate solutions and its adsorbed layer for the various regions of the adsorption isotherm (Fig. 4.18) (Somasundaran et al., 1986). Comparing the ratios thus obtained to the /e//m values of DNP in mixtures of ethanol and glycerol of known viscosities, a microviscosity value of 90 to 120 cPs is obtained for the adsorbed layer in contrast to a value of 8 cPs for micelles. The constancy of microviscosity as reported by DNP is indicative of the existence of a condensed surfactant assembly (solloids) that holds the probe. 

Fig. 4.18. (A) Dinaphthyl propane (DNP) fluorescence spectra in sodium-dodecyl sulfate (SDS) micellar solution and (B) SDS-alumina slurry [SDS]/[DNP] refers to ratio of micellized or adsorbed SDS to added DNP.

Intramolecular excimer formation of 1, -dinaphthylal kanes has been investigated in detail [319,320], Chandross and Dempster reported the first example of intramolecular photodimerization of l,3-di(l-naphthyl)propane (328), which was discovered during their intramolecular excimer study [321,322], Upon irradiation of 328 in methylcyclohexane, 328 formed 329, which is thermally unstable to give 330 (Scheme 92). Both 329 and 330 are converted substantially to 328 upon irradiation with 254-nm light. Similar irradiation of l,3-di(2-naphthyl)propane did not give any photocycloadduct. The authors assumed that the intramolecular cyclom-erization occurred via an intramolecular excimer. Davidson and Whelan reported further evidence for this assumption [320],... 

In addition, luminescence intensity and lifetime data obtained not only from the labelled polymer but also.from emission of dispersed naphthalene, acenaphthene and 1,1-dinaphthyl-l,3-propane (DNP) are briefly discussed. These measurements have provided information not only of relevance to the relaxation behaviour of the polymer matrix but also to the photophysies which occur therein and intramolecularly within the DNP. 

---