Complexes with Amine, Pyridine, and Stilbazole Ligands

1 Complexes with Amine, Pyridine, and Stilbazole Ligands 

A-Arylation of the 4,4 -bipyridinium cation leads to an even higher jSo(HRS) value (2, 410 x 10 esu) [37], and, by placing a trans-ethylene bridge between the pyridine and pyridinium rings of L, fio increases up to 50% [41]. 

Besides, replacement of a neutral L ligand such as 4-Me2N-CsH4N with a presumably N-coordinated thiocyanate anion (see 3) increases the electron-donating strength of the Ru° center and consequently the jSo(HRS) value to 513 x 10 ° esu [42]. The jSo values obtained by the HRS technique for these Ru° chromophores were confirmed by means of the method based on Stark spectroscopy [41,42]. Also, calculations based on TD-DFT gave values of jSq reasonably in agreement with the 

Within three series of pyridyl polyene chromophores 4, the /Iq values obtained by the HRS technique or Stark spectroscopy (about 100-600 x 10 ° esu) maximize when n = 2. This is in contrast with the behavior of known organic chromophores based on an electron-donor-acceptor system linked by a polyene bridge, in which /lo(HRS) increases steadily with the increase of the n delocalization of the polyene bridge [48, 49]. TD-DFT calculations show that the HOMO level of these 

Remarkably, the jSo(HRS) values of certain complexes (e.g., 1) can be reversibly and very effectively (10- to 20-fold) attenuated by a Ru /Ru° redox process involving chemical reagents such as H2O2 [39, 40, 43 5]. 

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