Piero Paoletti

Does a macrocyclic effect exist in the blue-to-yellow conversion of nickel(II) complexes with tetra-aza ligands?

Zur Untersuchung, ob und in welchem Ausmas die cyclische Natur eines Liganden das Gleichgewicht zwischen den paramagnetischen, blauen Komplexen (I) und den diamagnetischen, gelben Komplexen (II) beeinflust, wird die Thermodynamik dieser Umlagerung mit Komplexen mit dem Cyclus und den beiden linearen Analogen untersucht.

Thermodynamic and structural aspects of transition metal compounds. Polynuclear complexes of aza-macrocycles

A. Introduction 51 B. Macrocycles and macrobicycles able to incorporate several metal ions 52 C. Bis(macrocycles) 71 D. Bridged macrocyclic metal complexes 73 Acknowledgements 83 References 83

Potential ATPase mimics by polyammonium macrocycles: Criteria for catalytic activity

Abstract A series of polyammonium macrocycles, ranging in size from the 18-membered ring [18]aneN6 to the 36-membered [36]aneN12 were examined as potential ATPase mimics. The rates of hydrolysis of ATP were followed at pH 3.0 and 7.0 using 31P NMR and HPLC techniques. Stability constants as a function of degree of protonation, distribution curves for the ligands as a function of pH, and distribution curves for the mixed species of nucleotides, inorganic phosphate, and macrocycle were also determined. All of the macrocycles catalyzed the hydrolysis of ATP to some extent compared to noncatalyzed hydrolysis. A critical dependence on macrocyclic ring size was observed, with [21]aneN7 being the best catalyst at both pHs. Stability constants of the complexes formed between the phosphate species and macrocycle increase with increasing degree of protonation and decreasing ring size. The trend in stability constants for phosphate species was found to be PO43− > P2O74− > ATP4− > ADP3− > AMP2− for a given degree of protonation. The crystal structure of tetraprotonated [21]aneN7 was determined. The compound N7C14Cl4H41O crystallizes in the monoclinic space group P21 (#4) with unit cell dimensions a = 7.472(1), b = 19.480(2), c = 8.3638(9) A , β = 100.38(1)o, and V = 1197.4(3) A 3 . The structure was solved by direct methods and refined using full-matrix least-squares techniques to give a final R = 0.041 and Rw = 0.055.

Supramolecular interaction between adenosine 5′-triphosphate (ATP) and polycharged tetraazamacrocycles. Thermodynamic and 31P NMR studies

Abstract The interaction of adenosine 5′-triphosphate (ATP) with the tetraammonium macrocyclic receptors 1,1,4,4,7,7,10,10-octamethyl-1,4,7,10-tetraazacyclododecane tetrakis(iodide) (L1·4I) and 1,6,11,16-tetraazacycloeicosane (L2) in its fully protonated form, has been studied by potentiometry and 31 P NMR in water at I = 0.15 mol dm −3 and 25 °C H 4 L2 4+ reacts both with ATP 4− and HATP 3− to produce H 4 L2·ATP and (H 4 L2·HATP) + whose equilibrium constants are 6.46 × 10 3 and 1.10 x 10 3 , respectively. In the case of L1, in which the quaternarization of the nitrogen atoms prevents the formation of hydrogen bonds, no detectable interactions arise with ATP. These results are consistent with the hypothesis that the formation of hydrogen bonds play a role of major importance in the interaction between ATP and tetrammonium receptors.

Interaction of lead(II) with highly-dentate linear and cyclic polyamines

The interaction of Pb2+ with the macrocyclic amines 1,4,7,10,13,16-hexaazacyclooctadecane (L1), 1,4,7,10,13,16,19-heptaazacyclohenicosane (L2), 1,4,7,10,13,16,19,22-octaazacyclotetracosane (L3), 1,4,7,10,13,16,19,22,25-nonaazacycloheptacosane (L4), 1,4,7,10,13,16,19,22,25,28-decaazacyclotriacontane (L5), 1,4,7,10,13,16,19,22,25,28,31-undecaazacyclotritriacontane (L6) and 1,4,7,10,13,16,19,22,25,28,31,34-dodecaazacyclohexatriacontane (L7) belonging to the [3k]aneNg series and with their related open-chain, terminally methylated polyamines 1,14-bis(methylamino)-3,6,9,12-tetraazatetra-decane (L8), 1,17-bis(methylamino)-3,6,9,12,15-pentaazaheptadecane (L9), 1,20-bis(methylamino)-3,6,9,12,15,18-hexaazaicosane (L10) and 1,23-bis(methylamino)-3,6,9,12,15,18,21-heptaazatricosane (L11) has been studied by potentiometry at 298.1 K in 0.15 mol dm–3 NaClO4. The cyclic amines L1 and L2 form only mononuclear complexes, while L3–L5 can form both mono- and bi-nuclear species. The largest amines of this series L6 and L7 form bi- and tri-nuclear lead(II) complexes. Of the open-chain ligands, L8 forms only mononuclear complexes, while L9–L11 form both mono- and bi-nuclear species. The crystal structure of the solid compound [Pb2L5][ClO4]4 has been solved by X-ray diffraction analysis [space group P21/n, Z= 2, a= 9.052(9), b= 11.400(9), c= 18.689(8)A, β= 94.42(6)°, R= 0.082 and R′= 0.068]. It shows that both Pb2+ ions are tightly co-ordinated to four nitrogens of the macrocycle (Pb–N ranging from 2.27 to 2.71 A). A fifth nitrogen and three oxygens of two perchlorate anions are weakly interacting at much larger distances (Pb–N 3.04; Pb–O 2.98, 3.38, 3.41 A). The complex cation is situated around a crystallographic symmetry centre. The arrangement of the eight atoms around the lead ion is rather asymmetric leaving a zone free from co-ordinated donor atoms which is believed to be occupied by a lone pair of electrons.

Co-ordination tendency of [3k]aneNk polyazacycloalkanes. Thermodynamic study of solution equilibria

Equilibria between polyazacycloalkanes of the series [3k]aneNk(k= 3–11) and the bivalent metal ions of Mn through Zn have been studied. The stability constants (log K) for the complexes of Mn2+, Cu2+ and Fe2+ with 1,4,7,10,13,16-hexaazacyclooctadecane (L4), 1,4,7,10,13,16,19-heptaazacyclo-henicosane (L5) and 1,4,7,10,13,16,19,22-octaazacyclotetracosane (L6) have been determined potentiometrically in 0.15 mol dm–3 NaClO4 at 25°C: [MnL4]2+, 10.50; [MnL6]2+, 6.27; [CuL4]2+, 24.40; [CuL5]2+, 19.48; [Cu2L5]4+, 30.49; [Cu2L6]4+, 35.25; and [FeL5]2+ 12.09. The enthalpy changes (–ΔH°/kcal mol–1) for the formation of [CuL4]2+(23.9), [CuL5]2+(19.7) and [NiL5]2+(11.7) have been measured by means of microcalorimetric techniques. The results are discussed in terms of the increasing number of donor atoms and size of the macrocycles. As the size increases the co-ordination features of the metal compleses largely depend on the metal ion.

E.s.r. properties of some copper(II) polyamine complexes in nonaqueous solvents

Abstract An e.s.r. study of Copper(II) complexes with the following linear aliphatic polyamines: ethylenediamine, 1,3-diaminopropane, triethylenetetramine, 3,3′-diaminodipropylamine and N,N,N′,N″,N‴,N‴-hexamethyltriethylenetetramine has been carried out with the aim of providing information on the electronic ground state of the complexes. In addition information on the nature and extent of the interaction with the solvent has been obtained. Complementary data, namely electronic spectra and conductivity measurements, have been used to help provide the most reliable prediction of the stereochemistry of the complexes.

Di-and tri-palladium(II) polyazacycloalakane complexes. A case of deprotonated secondary nitrogen in solution and in solid state

Crystal structures of di- and tri-nuclear palladium(II) complexes with the azamacrocycles[18]aneN6 and [21]aneN7 have been solved by X-ray analysis; in the case of the trinuclear complex deprotonation of a secondary amino group occurs, both in solution and in the solid state.

1,10-Dimethyl-1,4,7,10,13,16-hexaazacyclooctadecane L and 1,4,7-trimethyl-1,4,7,10,13,16,19-heptaazacyclohenicosane L1: two new macrocyclic receptors for ATP binding. Synthesis, solution equilibria and the crystal structure of (H4L)(ClO4)4

The synthesis of two new methylated ligands 1,10-dimethyl-1,4,7,10,13,16-hexaazacyclooctadecane L and 1,4,7-trimethyl-1,4,7,10,13,16,19-heptaazacyclohenicosane L1 is described. Basicity constants and protonation enthalpies of both ligands have been determined by potentiometric and microcalorimetric measurements in 0.15 mol dm–3 NaClO4 at 298.1 K. The protonated forms of these cyclic polyamines bind ATP in solution. The equilibrium constants of the species formed have been determined (0.15 mol dm–3 NaClO4, 298.1 K). The results presented for L and L1 are compared with those previously obtained for the related ligands 1,4,7,10,13,16-hexaazacyclooctadecane, 1,4,7,10,13,16,19-heptaazacyclohenicosane and 1,4,7,13-tetramethyl-1,4,7,10,13,16-hexaazacyclooctadecane. Among these macrocycles Lis a selective receptor for ATP binding.The crystal structure of the compound (H4L)(ClO4)4[space group P21/c, a= 9.257(4), b= 8.600(2). c= 17.990(10)A, β= 101.74(4)°, V= 1402(1)A3, Z= 2] shows that the four charged ammonium groups point inside the macrocyclic cavity.

(PdCl4)2– inclusion into the deca-charged polyammonium receptor (H10[30]aneN10)10+([30]aneN10= 1,4,7,10,13,16,19,22,25,28-deca-azacyclotriacontane)

The title decaprotonated deca-azamacrocycle encapsulates the tetrachloropalladate(II) anion forming a ‘super complex’ whose crystal structure has been determined.