Photophysics of pi-conjugated metal-organic oligomers: aryleneethynylenes that contain the (bpy)Re(CO)(3)Cl chromophore.

A comprehensive study of a series of four monodisperse, metal-organic pi-conjugated oligomers of varying length is reported. The oligomers are based on the aryleneethynylene architecture, and they contain a 2,2'-bipyridine-5,5'-diyl (bpy) metal binding unit. The photophysical properties of the free oligomers and their complexes with the (L)Re(I)(CO)(3)X chromophore (where L = the bpy-oligomer and X = Cl or NCCH(3)) were explored by a variety of methods including electrochemistry, UV-visible absorption, variable temperature photoluminescence (PL), transient absorption (TA), and time-resolved electron paramagnetic spectroscopy (TREPR).

Spin-Echo Mapping Spectroscopy Applied to NQR.

A theoretical description of nuclear spin-echo Fourier-transform mapping spectroscopy (NSEFTMS) for broad NQR lines is derived from the time-domain spin-echo theory for a spin I = 32 system. The expression found for the effective broadband RF excitation profile is similar to that in NMR spectroscopy. The main difference is the angular dependence of the nutation frequency, but this does not change the overall behavior.