The isolation and characterization of new lanthanide complexes of formula [Ln(Q_L)₃(EtOH)(H₂O)], (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb; HQ_L = 1-phenyl-3-methyl-4-phenylacetylpyrazol-5-one) [Ln(Q_L)₃(H₂O)₂] (L = La or Lu), [Ln(Q_S)₃(EtOH)(H₂O)] (Ln = Tb or Eu; HQ_S = 1-phenyl-3-methyl-4-thienoylpyrazol-5-one, [Tb(Q_O)₃(EtOH)(H₂O)] (HQ_O = 1-phenyl-3-methyl-4-furanoylpyrazol-5-one) [Tb(Q_F)₃(H₂O)₂] (HQ_F = 1-phenyl-3-methyl-4-trifluoroacetylpyrazol-5-one) and [NBu₄][Ln(Q)₄] (Ln = Eu or Tb, Q = Q_F or Q_L) is reported. The crystal structure of the tris(β-diketonate) complexes [Nd(Q_L)₃(EtOH)(H₂O)], [Dy(Q_L)₃(EtOH)(H₂O)](EtOH), and [Eu(Q_S)₃(H₂O)(EtOH)] containing eight-coordinate lanthanide ions in a square antiprismatic environment has been determined. The coordination environment in the tetrakis complex [NBu₄][Eu(Q_F)₄] is also close to the square antiprismatic one. Photoluminescence (PL) and phosphorescence studies of selected derivatives are reported.

This review covers the types and applications of chemical inhibitors of gas hydrate formation in the oil and gas industry. The main directions of the development of new types of highly effective and environmentally safe “green” kinetic hydrate inhibitors (KHIs) based on biopolymers are analyzed. The structure, physicochemical properties, efficiency of gas hydrate formation inhibition, and commercial prospects of polysaccharides in preventing and controlling the formation of gas hydrates are considered. The criteria for their selection, current experimental data, and the mechanism of inhibition are presented. Recent research in the development of cost-effective, efficient, and biodegradable KHIs for industrial applications in the oil and gas industry is also presented.