Transition Metal Ion Complexes of 2,2′-Bipyridyl-3,3′-diol and 2,2′-Bipyridyl-3-ol: Spectroscopic Properties and Solvent-Dependent Binding Modes

Abstract

The complexation behaviour of 2,2′‐bipyridyl‐3,3′‐diol and 2,2′‐bipyridyl‐3‐ol, BP(OH)2 and BPOH, with various heavy and transition metal ions has been investigated in aqueous, alcoholic, and acetonitrile solutions. Whereas the complexes with paramagnetic ions and HgII are non‐fluorescent, ZnII and CdII form highly fluorescent complexes, their coordination geometries depending on the solvent proticity and hydrogen‐bond donating ability. Through a comparative study with the corresponding chelates of 2,2′‐bipyridyl (bipy), N,O‐coordination in a six‐membered ring chelate has been found to be the dominant binding mode in both the ZnII and CdII complexes in the protic solvents water and ethanol. Only for ZnII and BPOH is exclusive N,N′‐chelation found in acetonitrile. NMR measurements on BP(OH)2, BPOH, and bipy in the presence of ZnII and CdII in acetonitrile confirmed these findings.

Red-Emitting Polymerizable Guanidinium Dyes as Fluorescent Probes in Molecularly Imprinted Polymers for Glyphosate Detection

“…To further investigate this behavior, Job plots were constructed for GPS-TBA, with I in CHCl 3 and MeCN. The contribution of I-GPS-TBA to the changes in the absorption signal of the dye-template mixture (Y λ ) was plotted against the molar ratio of GPS-TBA [57]. In CHCl 3 , it was found that 2 moles of GPS-TBA could form a complex with 3 moles of I (I:GPS-TBA 1.5:1 stoichiometry, see Figure 3a and Figure S9a, Supplementary Material).…”

Fluorescent Oligopyridines and their Photo-Functionality as Tunable Fluorophores

“…As highly fluorescent conjugated polyarenes, alternating copolymers consisting of 1,4-diethynylbenzene and bpy units were synthesized [37]. Both linear rod-like -chain polymers, bpy-5,5'-diyl (94)(95)(96), and angularly linked polymers, bpy 4,4'-diyl (97-99, DP = 4-25), showed fluorescence in the range of 389 -456 nm ( = 0.45 -0.67 in toluene). The related model compounds (100-105) showed similar spectroscopic properties to the polymers, exhibiting quite efficient fluorescence ( ~1.0).…”