Isothiocyanate ligands

Six-coordinate complexes of several Fe porphyrins, having one pyridine and one isothiocyanate ligand, have been reported. Interestingly, the pyridine/A-bound thiocyanate anion combination appears to he close to the... 

Labelling with the isothiocyanate ligands has been effected by reaction with protein amine groups to form thiourea bonds. The coupled antibodies could be stored for months. The use of the cyclic dianhydride (CA-DTPA), 17 , has some disadvantage since one ligand carboxylate metal binding site is occupied in an acid amide bond to form a protein-linked diethylenetriaminetetraacetic acid (DTTA). 

Six-coordinate complexes of several Fe porphyrins, having one pyridine and one isothiocyanate ligand, have been reported. Interestingly, the pyridine/N-bound thiocyanate anion combination appears to lie close to the 5=1/2 — 5/2 spin crossover point for the TPPFe complex and, depending on the crystal lattice, exists as either a low-spin or a thermal equilibrium between a low-spin and a high-spin complex, while the OEPFe complex is high-spin at all temperatures. ... 

Calibration. Many approaches have been used to calibrate flow cytometric measurements. Including the comparison of flow and nonflow techniques (radiolabels, spectrofluorometry). In recent years, commercial standards have been introduced which are calibrated in fluorescein equivalents/particle (e.g., 3,000 or 500,000). With labeled ligands, calibration requires determining the relative quantum yield of the ligand compared to pure fluorescein and using the standards to analyze the amount bound on cells. Our ligands (fluorescein isothiocyanate derivatives) are typically 50% as fluorescent as fluorescein. 

Diamines can also react with only one equivalent of isothiocyanate to form bi-functionnal amine-thiourea ligands 59-68% yields obtained for several alkyl isothiocyanates. However, reaction of phenyhsocyanate with 1,2-diamines could also lead to the formation of the guanidine derivative by cyclisation and elimination of H2S (Scheme 4) [42,43]. 

Note that carbon monoxide inserts into the Zr-H bond of 1 (2 equiv.) to afford an T -formaldehydo-type complex [(Cp2ZrCl)]2(g-CH20) [200-202]. Iminoacyl zir-conocene complexes are formed after addition of 1 to isonitriles [203]. Carbon dioxide [183, 202] is reduced to formaldehyde with 1 (2 equiv.). C02-like molecules such as isocyanates RNCO [204], isothiocyanates RNCS [205], and carbodiimides RNCNR [204] are readily converted to the corresponding bidentate form-amido ligands. 

The DELFIA assay, the first effective lanthanide-based immunoassay, was developed and commercialized by the early 1980s.108-112 DELFIA (Dissociation Enhanced Lanthanide Fluoro-ImmunoAssay) is a heterogeneous assay which uses a lanthanide complex based on aminocarboxylate ligands such as EDTA, EGTA, or DTPA, linked to the antibody by reaction of appended isothiocyanate groups (e.g., complex (45)) with nucleophilic residues, particularly amines, on the protein surface (Figure 11). 

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