Chelation resonance enhancement

When the fluorescing atoms or molecules are placed inside such a microcavity, the fluorescence gets coupled to the MDR as an electromagnetic field. This results in alternatively enhancement or inhibition of the fluorescence depending on whether or not the fluorescence emission spectrally coincides with a cavity resonance. The effect of MDR on the radiative rate of chelated Europium ions [2] as well as the shortening of fluorescence lifetime of Rhodamine 6G due to the effect of MDR have been reported in microdroplets [3]. 

Valuable spectroscopic studies on the dithiolene chelated to Mo in various enzymes have been enhanced by the knowledge of the structure from X-ray diffraction. Plagued by interference of prosthetic groups—heme, flavin, iron-sulfur clusters—the majority of information has been gleaned from the DMSO reductase system. The spectroscopic tools of X-ray absorption spectroscopy (XAS), electronic ultraviolet/visible (UV/vis) spectroscopy, resonance Raman (RR), MCD, and various electron paramagnetic resonance techniques [EPR, electron spin echo envelope modulation (ESEEM), and electron nuclear double resonance (ENDOR)] have been particularly effective probes of the metal site. Of these, only MCD and RR have detected features attributable to the dithiolene unit. Selected results from a variety of studies are presented below, chosen because their focus is the Mo-dithiolene unit and organized according to method rather than to enzyme or type of active site. 

Jenkins, B.G., Armstrong, E., and Lauffer, R.B. (1991) Site-specific water proton relaxation enhancement of iron(III) chelates noncovalently bound to human serum albumin. Magnetic Resonance in Medicine, 17, 164-178. 

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