Hexaphyrin(1.0.1.0.0.0): An Expanded Porphyrin Ligand for the Actinide Cations Uranyl (UO22+) and Neptunyl (NpO2+)

Thermodynamic studies of sitting-atop (SAT) complexation of uranyl and free base meso -tetraarylporphyrins

“…Lomova and Andrianova [12] reported that reaction of H 2 tpp with uranyl acetate in phenol produced the double decker U(IV)(tpp) 2 and U(III)(tpp) 3 . In 2001 Sessler et al used an expanded porphyrin to coordinate UO 2þ 2 showing that the macrocycle twisted slightly to accommodate the uranyl while adopting an aromatic structure [13]. The first metal complex from the cyclo[n]pyrrole series of expanded porphyrins was formed when cyclo [6]pyrrole was treated with the uranyl cation under aerobic conditions [14].…”

Schiff base oligopyrrolic macrocycles as ligands for lanthanides and actinides

“…While not yet established unequivocally in the present instance, the idea of ligand oxidation in the context of actinide cation complexation is not new; it has been previously reported by our group in the case of isoamethyrin, 4 (Scheme 3), a formally 24 -electron expanded porphyrin that undergoes oxidation upon coordination with the [UO 2 ] 2+ or the [NpO 2 ] + cations to produce the corresponding 22 -electron derivative [16]. The result is an easy-to-visualize color change that makes isoamethyrin attractive as a possible colorimetric sensor for the actinide cations.…”

“…On the other hand, several actinide-containing Schiff base macrocycles have been reported by our group [4,[15][16][17][18]. Among these, perhaps the best studied has been 'alaskaphyrin' (2), a 2,5-diformylpyrrolederived Schiff base system that is characterized by its ease of synthesis and its robustness [15].…”

“…Grandephyrin contains an inner core that is similar in size to that present in isoamethyrin 4, mentioned above [16]. In light of this, salts of [UO 2 ] 2+ , [NpO 2 ] 2+ or [PuO] 2 2+ cations were added to methanolic solutions of the free base form of grandephyrin.…”

Interpretation and Prediction of Properties of Transition Metal Coordination Compounds

“…In transition metal coordination chemistry, the type of donor atoms and their arrangement around a metal center determine the properties of a complex to a large extent. Other factors related to the tuning of molecular properties by structural modifications are the variation of substituents at the periphery of a ligand to modify the solubility (used, e.g., for metal-ion-selective extractions; [81] note that hydrophobicity has also been proposed to change the properties of the metal center [82], and charged peripheral substituents have been shown to influence the electronics of the metal center in a similar way as electrostatic fields in metalloproteins are tuning the electronics of the reactive center [83]); substitution at the ligand periphery has also been used to modify the ligand conformation and therefore, for example, the complex stability; [84,85] and the modulation of the shape of the active transition metal ion site has been used to stabilize specific substrate-catalyst interactions and destabilize others (e.g., as used in the area of enantioselective catalysis [86] and for the stabilization of metastable intermediates in mechanistic biomimetic studies [87]). The role of the protein in enzymes in shaping the environment is another structural aspect of importance, and there are various examples of modeling these particular structural features [88][89][90].…”