Robert C. Luckay

Strong Metal Ion Size Based Selectivity of the Highly Preorganized Ligand PDA (1,10-Phenanthroline-2,9-dicarboxylic Acid) with Trivalent Metal Ions. A Crystallographic, Fluorometric, and Thermodynamic Study

The selectivity of the rigid ligand PDA (1,10-phenanthroline-2,9-dicarboxylic acid) for some M(III) (M = metal) ions is presented. The structure of [Fe(PDA(H)(1/2))(H(2)O)(3)] (ClO(4))(2).3H(2)O.(1)/(2)H(5)O(2) (1) is reported: triclinic, P1, a = 7.9022(16) A, b = 12.389(3) A, c = 13.031(3) A, alpha = 82.55(3) degrees , beta = 88.41(3) degrees , gamma = 78.27(3) degrees , V = 1238.6(4) A(3), Z = 2, R = 0.0489. The coordination geometry around the Fe(III) is close to a regular pentagonal bipyramid, with Fe-N lengths averaging 2.20 A, which is normal for a 1,10-phenanthroline type of ligand coordinated to seven-coordinate Fe(III). The Fe-O bonds to the carboxylate oxygens average 2.157 A, which is rather long compared to the average Fe-O length of 2.035 A to carboxylates in seven-coordinate Fe(III) complexes. The structure of 1 supports the idea that the Fe(III) is too small for ideal coordination in the cleft of PDA, and the structure shows that the Fe(III) adapts to this by inducing numerous small distortions in the structure of the PDA ligand. The log K(1) values for PDA at 25 degrees C in 0.1 M NaClO(4) were determined by UV spectroscopy with Al(III) (log K(1) = 6.9), Ga(III) (log K(1) = 9.7), In(III) (log K(1) = 19.7), Fe(III) (log K(1) = 20.0), and Bi(III) (log K(1) = 26.2). The low values of log K(1) for PDA with Al(III) and Ga(III) are because these ions are too small for the cleft in PDA, which requires a large metal ion with an ionic radius (r(+)) of 1.0 A. In(III) and Fe(III) (r(+) = 0.86 and 0.72 A for a coordination number (CN) of 7) are somewhat too small for the cleft in PDA but may adapt by increasing the coordination number, which increases the metal ion size, and have high log K(1) values. Very large log K(1) values are found, as expected, for Bi(III) (r(+) = 1.17 A, CN = 8), which fits the cleft quite well. Fluorescence studies show that Y(III) produces the largest CHEF (chelation enhanced fluorescence) effects, followed by La(III) and Lu(III), in the PDA complexes. Metal ions with nonfilled d or f subshells produce very large quenching of the fluorescence, as do heavy-metal ions such as In(III) and Bi(III), which have large spin-orbit coupling effects. The Al(III)/PDA complex produced an intense broad band at longer wavelength than the pi*-pi emissions of the PDA ligand, which is at a maximum at pH 6, and the possibility that this might reflect an exciplex, where one PDA ligand in the Al(III) complex pi-stacks with the excited state of a second PDA ligand, is discussed.

Competitive bulk liquid membrane transport of some metal ions using RC(S)NHP(S)(OiPr)2 as ionophores. Unusual supramolecular “honeycomb” aggregate of the polynuclear copper(I) complex of H2NC(S)NHP(S)(OiPr)2

Competitive transport experiments involving metal ions from an aqueous source phase through a chloroform membrane into an aqueous receiving phase have been carried out using a series of N-(thio)phosphorylated (thio)amide and thiourea ligands as ionophores in the organic phase. The source phase contained equimolar concentrations of Co(II), Ni(II), Cu(II), Zn(II), Ag(I), Cd(II) and Pb(II) with the source and receiving phases being buffered at different pH. Good transport properties were observed for Ag(I) in the case of (13). The best extraction properties have been shown by (3)L(1), (3)L(8), (2)L(7), (3)L(9) and (3)L(11) which contain an unsubstituted nitrogen atom at the C[double bond, length as m-dash]S groups ((3)L(1) and (3)L(9)), or a third nitrogen atom, capable of participating in additional coordination ((3)L(8), (2)L(7) and (3)L(11)). Reaction of Cu(NO(3))(2).6H(2)O with the potassium salt of the N-thiophosphorylated thiourea NH(2)C(S)NHP(S)(OiPr)(2) formed a new supramolecular Cu(I) complex, [{Cu(6)((2)L(1))(6)}{Cu(3)((2)L(1))(3)}.4Me(2)CO] that contains both trinuclear and hexanuclear forms in its solid state structure, and in solution.

Competitive bulk liquid membrane transport and solvent extraction of some metal ions using RC(S)NHP(X)(OiPr)2 (X = O, S) as ionophores. Formation of the polynuclear complex of [Ag(NC–NP(S)(OiPr)2)]n

Competitive transport experiments involving metal ions from an aqueous source phase through a chloroform membrane into an aqueous receiving phase have been carried out using a series of N-(thio)phosphorylated (thio)amide and thiourea ligands as the ionophore present in the organic phase. The source phase contained equimolar concentrations of Co(II), Ni(II), Cu(II), Zn(II), Ag(I), Cd(II) and Pb(II) with the source and receiving phases being buffered at a number of different pHs. Solvent extraction properties of the ligands towards the same metal cations under the same experimental conditions as for the transport were also studied. All ligands demonstrated 100% extraction of Ag(I). Reaction of AgNO(3) with the potassium salt of the N-thiophosphorylated thiourea NH(2)C(S)NHP(S)(OiPr)(2) gave a new supramolecular Ag(I) complex, [AgZ](n) (Z = {N[triple bond]C-NP(S)(OiPr)(2)}(-)) that contains both tri- and tetracoordinated Ag(I). The novel polynuclear Ag(I) complex [AgZ](n) described and structurally characterized by single crystal X-ray diffraction has no precedent.

Aerial oxidation of tetrahydrofuran to 2-hydroxotetrahydrofuran in the presence of a trimeric CuI complex [Cu3L3] (HL = tBuNHC(S)NHP(S)(OiPr)2) and trapping of the unstable product at recrystallization

The reaction of the potassium salt of N-thiophosphorylated thiourea tBuNHC(S)NHP(S)(OiPr)2 (HL) with Cu(NO3)2 in aqueous EtOH leads to the trinuclear [Cu3(tBuNHC(S)NP(S)(OiPr)2-S,S′)3] ([Cu3L3]) complex. It was established that [Cu3L3] provokes the aerobic oxidation of tetrahydrofuran to 2-hydroxotetrahydrofuran and traps the latter at crystallization.

Synthesis of ditopic ligands for the selective extraction of copper(II) nitrate and crystal structures of their Cu(II) complexes

Abstract We have synthesized two ditopic ligands for selective extraction of copper(II) nitrate. We also synthesized one cation-only binding analog for comparison. All three ligands were characterized by conventional techniques. Competitive two-phase metal ion solvent extraction experiments were performed at 25 °C over a period of 24 h. These ligands showed significant selectivity for Cu(II) ions, having the ditopic ligands extract 81 and 73% of the Cu(II) ions in a solution of different metal ions {Ni(II), Co(II), Cu(II), Zn(II), Cd(II), Pb(II)} at pH 5.09. Competitive transport experiments (water/chloroform/water) were undertaken employing each ligand separately as the ionophore in the membrane (chloroform) phase. No metal ion transport was observed, but a large concentration of Cu(II) was present in the membrane phase. Competitive anion extraction and transport were carried out with the ditopic ligands, yielding selective extraction and transport of nitrate. Furthermore, a pH isotherm of the best ditopic ligand (H2L2) with Cu(II) was determined from pH 1.0 to 6.0, producing a pH½ value of approximately 2.6. Finally, crystal structures of the ditopic ligands complexed with Cu(II) were determined and refined. The coordination geometry around the metal centers are distorted square planar and the Cu(II)-donor bond lengths fall within the normal range. Graphical Abstract

4-Bromo-N-(diisopropoxyphosphor-yl)benzamide

In the title compound, C13H19BrNO4P, the crystal structure is stabilized by intermolecular N—H⋯O hydrogen bonds between the phosphoryl O atom and the amide N atom which link the molecules into centrosymmetric dimers. These dimers are further packed into stacks along the c axis by intermolecular C—H⋯O and C—H⋯π interactions.

{1,5,9-Tris[(2S)-2-hydroxy­prop­yl]-1,5,9-triaza­cyclo­dodeca­ne}zinc(II) dinitrate monohydrate

In the title compound, [Zn(C18H39N3O3)](NO3)2·H2O, the coordination geometry around the central ZnII atom is distorted octahedral. The hydroxyl groups in the macrocyclic ligand and water molecules are engaged in O—H⋯O hydrogen bonding, which forms two-dimensional corrugated sheets comprising 34-membered rings. Neighbouring sheets are connected by C—H⋯O interactions.