Heterocycles with luminescent properties

Figure 2.21 Asymmetric unit of complex Eu(L )3 -phen [51b], (Reprinted with permission from S. Biju, D.B.A. Raj, M.L.P. Reddy and B.M. Kariuki, Synthesis, crystal structure, and luminescent properties of novel Eu + heterocyclic -diketonate complexes with bidentate nitrogen donors, Inorganic Chemistry, 45, 10651-10660, 2006. 2006 American Chemical Society.)...

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. 

Research in the chemistry of rhodium and iridium Af-heterocyclic carbene (NHC) complexes has extraordinarily evolved since 2000. A quick search for rhodiimi-NHC and iridiimi-NHC complexes in the SCl-expanded database, with a 2005-2013 timespan, results in more than 360 hits for rhodium, and more than 340 for iridiiun, which gives a good idea on the interest that rhodium and iridium NHC-based chemistry have achieved in the last few years. It is important to note that a nimiber of reviews and book chapters specifically concerning the chemistry of NHC-based compounds of rhodium and iridiiun have recently appeared [1]. This chapter will deal with all new aspects of the NHC-M (M = Rh, Ir) chemistry not reviewed before, and therefore is mainly restricted to the last 4-5 years. The chapter is classified into two main sections, the first of which deals with relevant structural and electronic features of Rh-NHC and Ir-NHC complexes, and the second with the catalytic applications of these compounds. While not pretending to be completely comprehensive, we have tried to describe the most relevant examples assigned to each section. Some other relevant applications of these complexes have not been considered, such as the emerging biochemical applications, mostly referred to Rh-NHC complexes [2], and the luminescent properties of some Ir-NHC complexes, mostly used for the fabrication of electro-optical devices [3]. 

A series of luminescent platinum(II) complexes have been prepared with a biphenyl dianion (bph) as ligand (Fig. 3.7)S These complexes have the formulae Pt(bph)(Et2S)2, Pt(bph)(MeCN)2, Pt(bph)en, and Pt(bph)(py)2, and although they do not strictly have a nitrogen-based heterocyclic ligand, they are included here because their photophysical properties are in many ways analogous. The biphenyl dianion was chosen as ligand for these complexes because it contains an empty... 

Sun W-YR, Chow AL-F, Li X-H, Yan JJ, Chui SS-Y, Che C-M. Luminescent cyclometalated platinum(II) complexes containing N-heterocyclic carbene ligands with potent in vitro and in vivo anti-cancer properties accumulate in cytoplasmic structures of cancer cells. Chem Set. 2011 2 728-736. 

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