Heterocyclic-substituted complexes metallo-1,2-enedithiolates

The study of emission 1,2-enedithiolates now represents a formidable body of literature, even though the chemistiy, photochemistry, and photophysical properties of metallo-l,2-enedithiolate complexes are not yet as well understood or developed as those of the group metallo-Vlll-diimine and metalloporphyrin complexes. However, recent developments in the synthesis of 1,2-enedithiolates have led to the discovery of room temperature emitters and complexes with useful properties. As new methods allow for the synthesis of yet unknown complexes in this family, the unique and useful properties of these complexes will become even more evident. Many of the heterocyclic-substituted 1,2-enedithiolates now available are dual emitters with a short-lived and analyte-quenchable long-lived excited states. Clearly, these dual emitters will have a unique place in the detection of quenching analytes since selective quenching of Ae long-lived excited state eliminates several problems encountered with luminescence-based sensing. 

In 1997, a new synthetic route [30-34,43] made available a range of heterocyclic-substituted metallo-l,2-enedithiolate complexes (Scheme 1). The heterocycle (Het) and R group are readily varied using this method. Metallo-1,2-enedithiolate complexes with appended pyridines, 2-pyrazine, and 2-quinoxaline are now available. While the R group is limited only by the availability of the a-bromo- or tosyl ketone required for this synthesis, to date only complexes where R = H, Me, and CH2CH2OAC (and several derivatives of CH2CH2OH) [34] have been prepared. 

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