Pendant Arm Derivatives Research Articles

Heteronuclear Gold(I)-Copper(I) Complexes with Thia- and Mixed Thia-Aza Macrocyclic Ligands: Synthesis, Structures and Optical Properties.

The reactivity of the heterometallic polynuclear complexes [{Au(R)2 }2 Cu2 (MeCN)2 ]n (R=C6 F5 , C6 Cl5 ) with the thioether crowns 1,4,7-trithiacyclononane (L1, [12]aneS3 ), 1,4,8,11-tetrathiacyclododecane (L2, [14]aneS4 ), 1,4,7,10,13,16,19,22-octathiacyclotetracosane (L3, [24]aneS8 ), and the quinoline functionalized pendant arm derivatives of the 12-membered mixed-donor macrocycles 1-aza-,4,7,10-trithiacyclododecane ([12]aneNS3 ) and 1,7-diaza-4,10-dithiacyclododecane ([12]aneN2 S2 ), L4 and L5, respectively, was investigated in THF solution. While with L4 and L5 only ionic compounds of general formulation [Cu(L)][Au(R)2 ] were isolated and structurally characterized (none of them featuring Au⋅⋅⋅Cu interactions), with L1-L3, beside similar ionic compounds, some heteronuclear complexes of general formulation [{Au(R)2 }{Cu(L)}] and featuring Au⋅⋅⋅Cu interactions were also obtained. All of them display rather unusual non-classical C-H⋅⋅⋅Au hydrogen interactions. The complexes display in the solid state different optical properties related to their structures, which have been studied experimentally and theoretically via TD-DFT calculations. In particular, all compounds of the type [{Au(R)2 }{Cu(L)}] featuring Au⋅⋅⋅Cu metallophilic interactions display luminescence in the solid state both at room temperature (RT) and at 77 K. On the contrary, ionic compounds of general formulation [Cu(L)][Au(R)2 ], except [Cu(L4)][Au(C6 F5 )2 ], are not luminescent.

Structural and Luminescence Properties of Heteronuclear Gold(I)/Thallium(I) Complexes Featuring Metallophilic Interactions Tuned by Quinoline Pendant Arm Derivatives of Mixed Donor Macrocycles.

Reaction of the heterometallic complex [{Au(C6F5)2}Tl]n with the quinoline pendant arm derivatives L1 and L2 of the mixed donor macrocycles [12]aneNS2O and PhenNS2 affords the new Au(I)/Tl(I) complexes [{Au(C6F5)2}Tl(L1)] (1), [{Au(C6F5)2}Tl(L2)] (2), [{Au(C6F5)2Tl}{Au(C6F5)2Tl(L1)}]2 (3), and [{Au(C6F5)2Tl}{Au(C6F5)2Tl(L2)}]n (4) depending on the reaction molar ratios used. These complexes present different optical properties strictly related to their structural features and to the presence of Au(I)···Tl(I) metallophilic interactions, which are finely tuned by the coordinating quinoline moiety and have been studied experimentally and theoretically via TD-DFT calculations.

An OFF–ON chemosensor for biological and environmental applications: sensing Cd2+ in water using catanionic vesicles and in living cells

A new OFF-ON fluorescent chemosensor (L(1)) for Cd(2+) recognition based on a 5-chloro-8-hydroxyquinoline pendant arm derivative of 1,4,7-triazacyclononane ([9]aneN3) will be presented and its photochemical features in an MeCN-H2O 1 : 1 (v/v) mixture, in pure water, after inclusion within catanionic vesicles, and in living cells will be discussed. The coordination properties of L(1) both in solution and in the solid state were preliminarily studied and its selectivity towards Cd(2+)versus a set of different metal ions (Cu(2+), Zn(2+), Cd(2+), Pb(2+), Al(3+), Hg(2+), Co(2+), Ni(2+), Mn(2+), Mg(2+), K(+), Ca(2+), Ag(+), and Na(+)) was verified in MeCN-H2O 1 : 1 (v/v). In water, upon addition of increasing amounts of Cd(2+) to L(1) an enhancement of the fluorescence emission was detected. To overcome this serious drawback, L(1) was dissolved in an innovative catanionic vesicular solution based on sodium bis(2-ethylhexyl) sulfosuccinate, a traditional surfactant, and 1-dodecyl-3-methylimidazolium bromide, an ionic liquid. When enclosed within the vesicle bilayers in water, L(1) restored its fluorescence emission property upon addition of Cd(2+). Remarkably, L(1) enters the cellular membrane of living cells thus allowing the detection of intracellular Cd(2+). These findings encourage the application of this new fluorescent chemosensor in real samples for histological and environmental analyses.

Fluorimetric Chemosensors Combined with Familiar CSPT Devices for the Selective Detection of Mercury(II) Ions

Abstract Fluorimetric and Computer Screen Photoassisted Technique (CSPT) studies on the binding properties of three coumarin pendant arm derivatives of mixed aza-thioether macrocyclic ligands (L1-L3), incorporated into PVC plasticized polymeric membranes, towards a number of different metal cations were carried out. An enhanced selectivity of the ligands towards Hg2+ion was detected. In particular, the DOS plasticized membrane containing L3 and tetrakis(p-chlorophenyl)borate, TpClPB-, as lipophilic anionic additive, displayed a strong fluorescence activation by Hg2+over the wide concentration range of 10-7to 10-3M. The influence of the ratio among ligand and lipophilic additive on the membrane performance was tested. In addition, the CSPT measurements showed that L3 possesses a unique selectivity towards Hg2+ion with respect to several common diverse cations. Moreover CSPT technique permits to perform the fast and low cost monitoring of mercury (II) ions, by application of familiar devices and a chemometric approach.

Inhibition of metal ion complexation by an N2O2-donor macrocycle by incorporation of an intramolecularly hydrogen-bonding pendant phenolic group

The synthesis and X-ray structure of a new pendant-arm derivative of a parent 14-membered N2O2-donor macrocycle bearing an N-substituted 6-methylene-2,4-dimethylphenol group is presented. A single crystal X-ray study shows a strong intramolecular hydrogen-bond between the pendant phenol proton and the tertiary nitrogen of the macrocyclic ring, which may inhibit its ability to bind with selected transition and post-transition metal ions.

Colorimetric response to anions by a “robust” copper(ii) complex of a [9]aneN3 pendant arm derivative: CN− and I− selective sensing

The 1 : 1 complex [Cu(L)](BF(4))(2)·MeCN (1) of the tetradentate ligand 1-(2-quinolinylmethyl)-1,4,7-triazacyclononane (L) selectively changes its colour in the presence of CN(-) in H(2)O and MeCN (without undergoing decomplexation from the macrocyclic ligand). The same complex in MeCN assumes different colours in the presence of CN(-) or I(-).

Hg2+ Detection by New Anthracene Pendant-Arm Derivatives of Mixed N/S- and N/S/O-Donor Macrocycles: Fluorescence, Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry and Density Functional Theory Studies

The optical response of four new anthracenylmethyl pendant-arm derivatives (L1-L4) of the macrocyclic ligands [12]aneNS(3), [12]aneNS(2)O, [15]aneNS(2)O(2), and [12]aneN(2)SO toward the metal ions Zn(2+), Cd(2+), Pb(2+), Cu(2+), Hg(2+), Ag(+), Fe(2+), Co(2+), Ni(2+), Mn(2+), Ca(2+), Na(+), Mg(2+), and K(+) was investigated in 1:1 (v/v) MeCN/H(2)O solutions. A strong chelation enhancement of quenching effect was observed on the fluorescent emission intensity of L2 as a consequence of the host-guest interaction with Hg(2+) and the formation of a 1:2 metal-to-ligand complex. Density functional theory calculations confirmed the formation of a sandwich-type complex between L2 and Hg(2+) as a favorable process. A matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry study using the four ligands as active MALDI probes was also performed. L1-L4 have also been explored as fluorescence chemosensors in microsamples using NANODROP technology.

Synthesis and Coordination Properties of Quinoline Pendant Arm Derivatives of [9]aneN3and [9]aneN2S as Fluorescent Zinc Sensors

The coordination chemistry of three new quinoline pendant arm derivatives of [9]aneN(3) (L(1), L(2)) and [9]aneN(2)S (L(3)) toward Cu(II), Zn(II), Cd(II), Hg(II), and Pb(II) has been investigated both in solution and in the solid state. The protonation constants for L(1)-L(3) and stability constants with the aforementioned metal ions have been determined potentiometrically in 0.10 M NMe(4)Cl MeCN/H(2)O (1:1 v/v) solution at 298.1 +/- 0.1 K; the measured values show that Cu(II) has the highest affinity for all three ligands, followed by Zn(II), Hg(II), Pb(II), and Cd(II). For each metal ion considered, 1:1 complexes with L(1)-L(3) have also been isolated in the solid state and [Cu(L(1))](BF(4))(2) (1), [Zn(L(1))](BF(4))(2) (2), [Cd(L(1))](ClO(4))(2) (3), [Hg(L(1))](NO(3))(2) (4), [Pb(L(1))](ClO(4))(2) x MeCN (5), [Zn(2)Cl(2)(L(2))(2)](BF(4))(2) x 1/2 MeNO(2) x H(2)O (6), [Cu(L(3))](ClO(4))(2) (7), [Zn(L(3))(NO(3))]NO(3) (8), [Cd(L(3))(NO(3))(0.82)Cl(0.18)]NO(3) (9), and [Hg(L(3))](ClO(4))(2) x MeCN (10) have also been characterized by X-ray crystallography. The optical response of L(1)-L(3) to the presence of the above-mentioned metal ions has been investigated in MeCN/H(2)O (1:1 v/v) and H(2)O solutions. All three ligands show a stronger "OFF-ON" CHEF (chelation enhancement of fluorescence) effect in the Zn(II) complexes than in the Cd(II) complexes in both media. The results have been examined by considering the ratio I(rel)(Zn(II))/I(rel)(Cd(II)), within the emerging idea that the relative strength of the CHEF effect for the small Zn(II) ion as compared to larger Cd(II) ion might be determined by steric crowding in the corresponding complexes with quinoline-based fluorescent chemosensors.

Synthesis, structures and properties of cobalt(III) and iron(III) complexes with a new triazamacrocycle, 1,4-diacetate-1,4,7-triazacyclodecane

A new bidisplaced acetate functionalized pendant arm derivative, 1,4-diacetate-1,4,7-triazacyclodecane (L) and its corresponding Co(III), Fe(III) complexes [CoLCl] (1) and [FeLCl]2 · 3H2O (2) were synthesized and characterized by elemental analysis, IR spectra,UV–Vis spectra, HNMR, MS, XPRD, TGA and single-crystal X-ray diffraction analysis. The crystal structure shows the metal ions in the complexes have similar coordination six-coordinate, by three nitrogens and two oxygens of the chelate ligand, and a chloride. Through calculation of the twist angle, we discover 1 forms a distorted octahedral geometry while 2 forms a distorted-prismatic geometry. In 2, there are abundant hydrogen bonds between the oxygen atoms of water and the nitrogens and oxygens of the ligand, resulting in a two-dimensional supramolecular network with a regular triatomic water cluster. The thermal gravimetric analyses of the two complexes are also given.

Binding and Structural Aspects of Nitrile‐ and Amino‐Functionalized Pendant Arm Derivatives of 1,4,7‐Triazacyclononane (|9|aneN3)

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1-(3-Aminopropyl)-4,7-dithia-1-azacyclononane-κ4N,N′,S,S′]bis(dimethylformamide-κO)nickel(II) bis(tetraphenylborate) acetonitrile disolvate

In the title complex, [Ni(C3H7NO)2(C9H20N2S2)](C24H20B)2·2CH3CN, the metal centre has a distorted octahedral environment, with four coordination sites occupied by two N- and two S-donor atoms from a 3-amino­propyl pendant arm derivative of the nine-membered macrocycle 1-aza-4,7-di­thia­cyclo­nonane, and the remaining two positions by two mutually cis di­methyl­form­amide ligands.

Coordination chemistry of N-aminopropyl pendant arm derivatives of mixed N/S-, and N/S/O-donor macrocycles, and construction of selective fluorimetric chemosensors for heavy metal ions

The coordination chemistry of the N-aminopropyl pendant arm derivatives (L1c-4c) of the mixed donor macrocyclic ligands [12]aneNS2O, [12]aneNS3, [12]aneN2SO, and [15]aneNS2O2(L1a-4a) towards Cu(II), Zn(II), Cd(II), Hg(II), and Pb(II) in aqueous solution has been investigated. The protonation and stability constants with the aforementioned metal ions were determined potentiometrically and compared, where possible, with those of the unfunctionalised macrocycles. The measured values show that Hg(II) and Cu(II) in water have the highest affinity for all ligands considered, with the N-aminopropyl pendant arm weakly coordinating the metal centres. Crystals suitable for X-ray diffraction analysis were grown for the perchlorate salt (H2L1c)(ClO4)2.dmf, and for the 1 : 1 complexes [Cd(L3a)(NO3)2](1), [Cu(L4a)dmf](ClO4)2(2), [Zn(L1c)(ClO4)]ClO4(3), [Cd(L1c)(NO3)]NO3(4), and [Hg(L2c)](ClO4)2(5). Their structures show the macrocyclic ligands adopting a folded conformation, which for the 12-membered systems can be either [2424] or [3333] depending on the nature of the metal ion. L1c-4c were also functionalised at the primary amino pendant group with different fluorogenic subunits. In particular the N-dansylamidopropyl (Lnd, n= 1-4), and the N-(9-anthracenylmethyl)aminopropyl (Lne, n= 1, 2, 4, ) pendant arm derivatives of L1a-4a were synthesised and their optical responses to the above mentioned metal ions were investigated in MeCN/H2O (4 : 1 v/v) solutions.

A new pyridine-based 12-membered macrocycle functionalised with different fluorescent subunits; coordination chemistry towards CuII, ZnII, CdII, HgII, and PbII

The coordination chemistry of the new pyridine-based, N2S2-donating 12-membered macrocycle 2,8-dithia-5-aza-2,6-pyridinophane (L1) towards Cu(II), Zn(II), Cd(II), Hg(II), and Pb(II) has been investigated both in aqueous solution and in the solid state. The protonation constants for L1 and stability constants with the aforementioned metal ions have been determined potentiometrically and compared with those of ligand L2, which contains a N-aminopropyl side arm. The measured values show that Hg(II) in water has the highest affinity for both ligands followed by Cu(II), Cd(II), Pb(II), and Zn(II). For each metal ion considered, 1:1 complexes with L1 have also been isolated in the solid state, those of Cu(II) and Zn(II) having also been characterised by X-ray crystallography. In both complexes L1 adopts a folded conformation and the coordination environments around the two metal centres are very similar: four positions of a distorted octahedral coordination sphere are occupied by the donor atoms of the macrocyclic ligand, and the two mutually cis-positions unoccupied by L1 accommodate monodentate NO3- ligands. The macrocycle L1 has then been functionalised with different fluorogenic subunits. In particular, the N-dansylamidopropyl (L3), N-(9-anthracenyl)methyl (L4), and N-(8-hydroxy-2-quinolinyl)methyl (L5) pendant arm derivatives of L1 have been synthesised and their optical response to the above mentioned metal ions investigated in MeCN/H2O (4:1 v/v) solutions.

Co-ordination chemistry of amino pendant arm derivatives of 1,4,7-triazacyclononane.

The binding properties of 1,4,7-triazacyclononane ([9]aneN3) to metal cations can be adapted through sequential functionalisation of the secondary amines with aminoethyl or aminopropyl pendant arms to generate ligands with increasing numbers of donor atoms. The new amino functionalised pendant arm derivative of 1,4,7-triazacyclononane ([9]aneN3), L1, has been synthesised and its salt [H2L1]Cl2 characterised by X-ray diffraction. The protonation constants of the ligands L1-L4 having one, two or three aminoethyl or three aminopropyl pendant arms, respectively, on the [9]aneN3 framework, and the thermodynamic stabilities of their mononuclear complexes with CuII and ZnII have been investigated by potentiometric measurements in aqueous solutions. In order to discern the protonation sites of ligands L1-L4, 1H NMR spectroscopic studies were performed in D2O as a function of pH. While the stability constants of the CuII complexes increase on going from L1 to L2 and then decrease on going from L2 to L3 and L4, those for ZnII complexes increase from L1 to L3 and then decrease for L4. The X-ray crystal structures of the complexes [Cu(L1)(Br)]Br, [Zn(L1)(NO3)]NO3, [Cu(L2)](ClO4)2, [Ni(L2)(MeCN)](BF4)2, [Zn(L4)](BF4)2.MeCN and [Mn(L4)](NO3)2.1/2H2O have been determined. In both [Cu(L1)(Br)]Br and [Zn(L1)(NO3)]NO3 the metal ion is five co-ordinate and bound by four N-donors of the macrocyclic ligand and by one of the two counter-anions. The crystal structures of [Cu(L2)](ClO4)2 and [Ni(L2)(MeCN)](BF4)2 show the metal centre in slightly distorted square-based pyramidal and octahedral geometry, respectively, with a MeCN molecule completing the co-ordination sphere around NiII in the latter. In both [Zn(L4)](BF4)2.MeCN and [Mn(L4)](NO3)2.1/2H2O the metal ion is bound by all six N-donors of the macrocyclic ligand in a distorted octahedral geometry. Interestingly, and in agreement with the solution studies and with the marked preference of CuII to assume a square-based pyramidal geometry with these types of ligands, the reaction of L4 with one equivalent of Cu(BF4)2.4H2O in MeOH at room temperature yields a square-based pyramidal five co-ordinate CuII complex [Cu(L6)](BF4)2 where one of the three propylamino pendant arms of the starting ligand has been cleaved to give L6.

Coordination Chemistry of Nitrile and Amino Pendant Arm Derivatives of [9]aneN2S and [9]aneNS2 with PdII and CuII

AbstractPalladium(II) and copper(II) complexes [Pd(L1)Cl2], [Pd(L3)Cl2], [Cu(L1)Cl2], [Cu(L3)Cl2], [Pd(L2)][BF4]2, [Pd(L4)Cl]BF4, [Cu(L2)][NO3]2 and [Cu(L4)Cl]PF6 of the nitrile (L1 and L3) and amino (L2 and L4) pendant arm derivatives of 1‐thia‐4,7‐diazacyclononane ([9]aneN2S) and 7‐aza‐1,4‐dithiacyclononane ([9]aneNS2) have been prepared and fully characterised. In each case, a square‐pyramidal coordination sphere is observed at both metal ions with either one or two Cl− anions completing the donor set. The tridentate nine‐membered macrocyclic moiety adopts a [333] conformation in all the complexes obtained. The five‐membered chelate rings involving the donor atoms of the basal plane adopt a gauche configuration with very similar degrees of puckering. The “innocent” nitrile pendant arms in L1 and L3 do not bind to the metal ions, but still appear to influence the binding of the tridentate macrocyclic frameworks via the tertiary amine sites. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Steric effects caused by N-alkylation of the tripodal chelator N,N′,N″-tris(2-pyridylmethyl)-cis,cis-1,3,5-triaminocyclohexane (tachpyr): structural and electronic properties of the Mn(ii), Co(ii), Ni(ii), Cu(ii) and Zn(ii) complexes

The effects of steric hindrance on the complexation of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) by chelators based on cis,cis-1,3,5-triaminocyclohexane (tach) have been studied. The chelators studied are the 2-methylpyridyl pendant-arm derivatives of tach, ‘tachpyr’ (N,N′,N″-tris(2-pyridylmethyl)-cis,cis-1,3,5-triaminocyclohexane), and the N-alkylated analogs ‘(N–Me)3tachpyr’ (N,N′,N″-trimethyl-N,N′,N″-tris(2-pyridylmethyl)-cis,cis-1,3,5-triaminocyclohexane) and ‘(N–Et)3tachpyr’ (N,N′,N″-triethyl-N,N′,N″-tris(2-pyridylmethyl)-cis,cis-1,3,5-triaminocyclohexane). Hexacoordinate complexes, [MIIL]X2 resulted from reaction of the appropriate metal ion salts with L in alcoholic medium (M = Mn, Co, Ni, Cu, Zn; L = tachpyr, (N–Me)3tachpyr, (N–Et)3tachpyr; X = ClO4−, NO3−, Cl−). The Mn(II) and Co(II) complexes have high-spin electron configurations, based on solution magnetic susceptibility, electronic spectral and/or X-ray crystallographic studies. However, solution visible-near IR electronic spectra and single-crystal X-ray crystallography demonstrate weakened bonding in the complexes of (N–R)3tachpyr relative to tachpyr, due to steric effects of methyl or ethyl groups on coordinated tach amines. Structures of [Zn(tachpyr)]2+ and [Ni(tachpyr)]2+ indicate a clear preference of tachpyr and derivatives for octahedral geometry, while [Cu((N–Me)3tachpyr)]2+ exhibits a classic Jahn–Teller tetragonal distortion. The complex [Mn(tachpyr)](ClO4)2 demonstrates a striking influence of the metal ion on the coordination geometry, with a trigonal-prismatic coordination of Mn(II) and considerable distortion of the tach-amino donor groups. The coordination geometry and distortions are attributed to the large size of high-spin d5 Mn(II) and the absence of ligand-field stabilization energy, coupled with the observed preference of tachpyr derivatives for octahedral geometry. The [MII(tachpyr)]2+ complexes (M = Co, Ni, Cu and Zn) are inert in aqueous pH 5.5 media. However, all metal complexes of N-alkylated tachpyr, as well as [Mn(tachpyr)](ClO4)2, dissociate metal ion in aqueous pH 5.5 medium, consistent with their steric hindrance and distortions respectively.

Nitrile functionalised pendant-arm derivatives of aza- and mixed donor macrocyclic ligands as new building blocks for inorganic crystal engineering

Download options Please wait... Supplementary files Crystal structure data TXT (120K) Article information DOI https://doi.org/10.1039/B110134J Article type Paper Submitted 16 Nov 2001 Accepted 24 Jan 2002 First published 26 Mar 2002 Download Citation J. Chem. Soc., Dalton Trans., 2002, 1662-1670 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Nitrile functionalised pendant-arm derivatives of aza- and mixed donor macrocyclic ligands as new building blocks for inorganic crystal engineering L. Tei, A. J. Blake, P. A. Cooke, C. Caltagirone, F. Demartin, V. Lippolis, F. Morale, C. Wilson and M. Schröder, J. Chem. Soc., Dalton Trans., 2002, 1662 DOI: 10.1039/B110134J To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Search articles by author Lorenzo Tei Alexander J. Blake Paul A. Cooke Claudia Caltagirone Francesco Demartin Vito Lippolis Francesca Morale Claire Wilson Martin Schröder

New Macrocyclic Ligands. XII. Phosphonic and Phosphinic Acid Pendant Arm Derivatives of Mixed Donor Macrocycles: Towards New Selective Reagents for Lead(II)

The synthesis of new bis-phosphonic, -phosphinic and -phenylphosphinic acid pendant-arm derivatives of a 15-membered, N 2 O 2 -donor macrocyclic ring is described. Thermodynamic stabilities of the 1:1 (metal:ligand) complexes of cobalt(II), nickel(II), zinc(II), silver(I), cadmium(II) and lead(II) with the bisphenylphosphinic acid derivative have been determined in 95% methanol (I = 0.1, NEt4ClO 4; 25°C). Along the above metal-ion series, this ligand forms its most stable complex with lead(II).

Nitrile functionalised pendant-arm derivatives of [9]aneN3 as new multidentate ligands for inorganic crystal engineering ([9]aneN3 = 1,4,7-triazacyclononane)

Functionalised pendant-arm derivatives of [9]aneN3 have been used as building blocks for the synthesis of inorganic multi-dimensional networks in the presence of AgI.

Stability and Structure of Activated Macrocycles. Ligands with Biological Applications.

Single p-toluic acid pendant groups were attached to 1,4,7,10,13-pentaazacyclopentadecane (15aneN5) and 1,4,8,11-tetraazacyclotetradecane (cyclam) to prepare bifunctional reagents for radiolabeling monoclonal antibodies with (64,67)Cu. The ligands are 1,4,7,10,13-pentaazacyclopentadecane-1-(alpha-1,4-toluic acid) (PCBA) and 1,4,8,11-tetraazacyclotetradecane-1-(alpha-1,4-toluic acid) (CPTA). For the parent macrocycles and their pendant arm derivatives, the 1:1 Cu(2+) complexes dissociate only below pH 2. At pH 0.0 and 25 degrees C the CPTA-Cu complex has a half-life toward complete dissociation of 24 days. A new approach was developed for the estimation of the Cu(2+) stability constant for the kinetically robust CPTA. All other formation constants were determined at 25.0 degrees C with batch spectrophotometric techniques. Potentiometric titrations were used to determine the protonation constants of the macrocyclic ligands as well as of the metal chelates. The protonation constants, stability constants, and pM's are discussed in terms of both molecular mechanics calculations and the ligands' potential applicability as copper(II) radiopharmaceuticals.