Macrocyclic Complexes Research Articles

Chlorin e6 13(N)-methylamide-15,17-dimethyl ester and its nickel complex as the inducers of chiral nematic liquid crystals

To search for new effective inducers of helical liquid-crystalline phases, chlorin e6 13 (N)-methylamide-15,17-dimethyl ester (MADMECl) and its nickel complex (Ni-MADMECl) were studied. An increase in the optical activity of the chlorin e6 derivative upon complexation with nickel, associated with a distortion of the macrocycle structure, was established by circular dichroism spectroscopy and quantum chemistry. The introduction of a macrocyclic complex into binary LC mixtures based on cyanobiphenyls (CB-2) and Schiff bases (SB-2), as well as the macrocyclic ligand MADMECl in CB-2, was shown to induce the formation of helical LC phases with high helical twisting power (maximum HTP = 409 μm−1 for the mixture CB-2 + Ni-MADMECl). The HTP decreases with an increase in the additive concentration. The assessment of the dopant influence on the LC thermal stability was carried out. The temperature dependences of the permittivity components of the studied liquid-crystalline solutions were obtained at different dopant concentrations. The relationship between the dielectric anisotropy and the helical pitch is established due to the 3D compensation of molecular dipoles. Quantum-chemical simulation of dopant-LC solvates was performed. The influence of the energy of intermolecular interaction on the efficiency of nematic phase twisting was ascertained. The contribution of supramolecular chirality to the process of chiral induction was detected.

New 15-membered macrocyclic Schiff base ligand; synthesis some Cd(II), Mn(II) and Zn(II) complexes, crystal structure, cytotoxicity, antibacterial and antioxidant activity

Herein, we aim at preparing 15-membered-ring symmetrical pentaaza macrocyclic Schiff base complexes using a template approach, based on the condensation reaction of an amine containing piperazine moiety, 2,2-(piperazine1,4-diyl)dianiline, and 2,6-diacetylpyridine in 1:1 mol ratio while Cd(II), Mn(II) and Zn(II) metal ions are present. Moreover, FT-IR, mass spectrometry, magnetic susceptibility measurements, UV–Vis and, 1H and 13C NMR spectroscopy were used to characterize these Schiff base complexes. Besides, the structure of [C25H25N5CdBr][ClO4] was determined using a single crystal X-ray structural analysis. Being in a pentagonal planar coordination environment, the Cd atom is surrounded by a Br atom in the apical position and 5 nitrogen atoms in the pentagonal plane. We also aimed at screening the synthesized complexes to investigate their antioxidant activities applying the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging assay. also, their bactericidal activity was evaluated using a paper disk diffusion method against both Gram-negative and Gram-positive bacteria, revealing a strong antioxidant activity and moderate effectiveness against all the tested bacteria. Finally, it is worth mentioning that the complex cytotoxicity was evaluated against MCF-7 (breast) and A549 (lung) adenocarcinoma cells. Generally, as compared to [ZnLBr]ClO4 possessed a greater cytotoxic effect against the tested cells.

Rac-1,8-Bis(2-carbamoyleth-yl)-5,5,7,12,12,14-hexa-methyl-1,4,8,11-tetra-aza-cyclo-tetra-deca-ne]copper(II) di-acetate tetra-hydrate: crystal structure and Hirshfeld surface analysis.

The title CuII macrocyclic complex salt tetra-hydrate, [Cu(C22H46N6O2)](C2H3O2)2·4H2O, sees the metal atom located on a centre of inversion and coordinated within a 4+2 (N4O2) tetra-gonally distorted coordination geometry; the N atoms are derived from the macrocycle and the O atoms from weakly associated [3.2048 (15) Å] acetate anions. Further stability to the three-ion aggregate is provided by intra-molecular amine-N-H⋯O(carboxyl-ate) hydrogen bonds. Hydrogen bonding is also prominent in the mol-ecular packing with amide-N-H⋯O(amide) inter-actions, leading to eight-membered {⋯HNCO}2 synthons, amide-N-H⋯O(water), water-O-H⋯O(carboxyl-ate) and water-O-H⋯O(water) hydrogen bonds featuring within the three-dimensional architecture. The calculated Hirshfeld surfaces for the individual components of the asymmetric unit differentiate the water mol-ecules owing to their distinctive supra-molecular association. For each of the anion and cation, H⋯H contacts predominate (50.7 and 65.2%, respectively) followed by H⋯O/O⋯H contacts (44.5 and 29.9%, respectively).

Synthesis and Characterization of CoII Macrocycles and its Use for Promoting Hydrolysis of Esters

The design and synthesis of hydrolytically active macrocycles mimic the substrate selectivity and rate enhancements for the hydrolysis of various organic substrates in high/low temperatures and extreme pH conditions, which is extremely challenging. In the present study, we synthesized two CoIIHMTAA-14 and CoIIHMTAA-16 macrocycles (HMTAA=hexamethyl-dibenzo-tetraaza-azulene) and used them to promote the hydrolysis of 4-nitrophenyl-2-benzamide carbonate and 4-nitrophenyl-4-benzamide carbonate esters. The effect of pH on hydrolysis of the carbonate esters was also studied at different pH 4.0, 6.5, and 8.5. The results of these studies showed that the reaction follows the first order with respect to ester concentration and is independent of the medium pH and water concentration. For the account of mechanism, hydrolysis of 4-nitrophenyl-2-benzamide carbonate and 4-nitrophenyl-4-benzamide carbonate proceeds either through oxygen or nitrogen intermolecular attack and normal H2O or OH- attacks, respectively. The plots of logkobs vs. pKa of the conjugate acid nucleophile showed leveling beyond pKa of about β = 0.3. The present macrocyclic complexes were found to provide enhanced hydrolysis of the esters.

Synthesis, Characterization and Biological Screening of Alkylene Dithiophosphate Derivatives of Macrocyclic Complexes of Pb (II)

Alkylenedithiophosphate derivatives of macrocyclic complexes of Pb (II), having N4S4 potential donors, of the general formula, [Pb(L){S2P(OR)2}2] where L=macrocyclic ligands L1, L2, L3, L4 and L5; R= C2H5-, C3H7n or C3H7i have been synthesized from the reaction of [Pb(L)X2(where X= Clˉ, NO3ˉ or CH3COOˉ) with sodium Alkylenedithiophosphate in 1:2 molar ratios in THF. These complexes have been characterized by elemental analysis, molar conductance, molecular weight determinations, IR, 1H, 13C NMR. Macrocyclic Complexes of Pb (II) derivatives have been studied by screening them Aspergillus flavus, Fusarium oxysporum, Alternaria alternata and bacteria like Salmonella typhi and Bacillus subtili. Alkylenedithiophosphate derivatives were found to be more fungitoxic and antibacterial than their corresponding macrocyclic complexes.

Cobalt-N4 macrocyclic complexes for heterogeneous electrocatalysis of the CO2 reduction reaction

Metal-N4 (M-N4) macrocyclic complexes are interesting electrocatalysts due to their well-defined structures and rich molecular tuning. Among them, metal phthalocyanines have been widely studied for the carbon dioxide reduction reaction (CO2RR) in heterogeneous systems and demonstrated good electrocatalytic performance. However, other complexes like metal corroles and metal porphyrins are much less explored, and often show inferior performances. In this study, three cobalt macrocyclic complexes, cobalt phthalocyanine, cobalt meso-tetraphenylporphyrin, and cobalt meso-triphenylcorrole (CoPc, CoTPP and CoTPC) are investigated in heterogeneous electrocatalysis of CO2RR. Although CoPc/carbon nanotube (CNT) hybrid exhibits high electrocatalytic activity, CNT hybridization does not work for CoTPC and CoTPP that hold weak interactions with CNTs. By the drop-dry method with a high molecular loading of 5.4 × 10–7 mol cm–2, CoTPC and CoTPP could deliver appreciable electrode activities. Poly(4-vinylpyridine) (PVP) introduction is further demonstrated as a facile method to afford enhanced activities for CoTPP at low molecular loadings through enhancing molecule-substrate interactions. The partial current density of carbon monoxide for CoTPP+CNT/PVP is around 8 times higher than the sample without PVP at –0.67 V versus reversible hydrogen electrode. This work provides solutions to enhance the electrode activities of molecular electrocatalysts with weak substrate interactions in heterogeneous systems.

Sorting Phenomena and Chirality Transfer in Fluoride-Bridged Macrocyclic Rare Earth Complexes.

The reaction of fluoride anions with mononuclear lanthanide(III) and yttrium(III) hexaaza-macrocyclic complexes results in the formation of dinuclear fluoride-bridged complexes. As indicated by X-ray crystal structures, in these complexes two metal ions bound by the macrocycles are linked by two or three bridging fluoride anions, depending on the type of the macrocycle. In the case of the chiral hexaaza-macrocycle L1 derived from trans-1,2-diaminocyclohexane, the formation of these μ2-fluorido dinuclear complexes is accompanied by enantiomeric self-recognition of macrocyclic units. In contrast, this kind of recognition is not observed in the case of complexes of the chiral macrocycle L2 derived from 1,2-diphenylethylenediamine. The reaction of fluoride with a mixture of mononuclear complexes of L1 and L2, containing two different Ln(III) ions, results in narcissistic sorting of macrocyclic units. Conversely, a similar reaction involving mononuclear complexes of L1 and complexes of achiral macrocycle L3 based on ethylenediamine results in sociable sorting of macrocyclic units and preferable formation of heterodinuclear complexes. In addition, formation of these heterodinuclear complexes is accompanied by chirality transfer from the chiral macrocycle L1 to the achiral macrocycle L3 as indicated by CPL and CD spectra.

Effects of Protonation State on Electrocatalytic CO2 Reduction by a Cobalt Aminopyridine Macrocyclic Complex.

A critical component in the reduction of CO2 to CO and H2O is the delivery of 2 equiv of protons and electrons to the CO2 molecule. The timing and sequencing of these proton and electron transfer steps are essential factors in directing the activity and selectivity for catalytic CO2 reduction. In previous studies, we have reported a series of macrocyclic aminopyridine cobalt complexes capable of reducing CO2 to CO with high faradaic efficiencies. Kinetic investigations reveal a relationship between the observed rate constant (kobs) and the number of pendant amine hydrogen bond donors minus one, suggesting the presence of a deprotonated active catalytic state. Herein, we investigate the feasibility of these proposed deprotonated complexes toward CO2 reduction. Two deprotonated derivatives, Co(L4-) and Co(L2-), of the tetraamino macrocycle Co(L) were independently synthesized and structurally characterized revealing extensive delocalization of the negative charge upon deprotonation. 1H nuclear magnetic resonance spectroscopy and ultraviolet-visible titration studies confirm that under catalytic conditions, the active form of the catalyst gradually becomes deprotonated, supporting thus the ndonor - 1 relationship with kobs. Electrochemical studies of Co(L4-) reveal that this deprotonated analogue is competent for electrocatalysis upon addition of an exogenous weak acid source, such as 2,2,2-trifluoroethanol, resulting in faradaic efficiencies for CO2-to-CO conversion identical to those observed with the fully protonated derivative (>98%).

Copper macrocyclic complex with trans-di[benzo]-porphyrazine and two oxo ligands: DFT quantum-chemical design

Based on the results of a quantum chemical calculation using the DFT method in the OPBE/TZVP and B3PW91/TZVP, the possibility of the existence of a copper heteroligand complex with trans-di[benzo]derivative of 3,7,11,15-tetraazaporphine (trans-di[benzo]porphyrazine) and two oxygen (O[Formula: see text] ions that is still unknown for this element was shown. In addition, the data on the structural parameters, the multiplicity of the ground state, NBO analysis and standard thermodynamic parameters of formation (standard enthalpy [Formula: see text], entropy [Formula: see text] and Gibbs’s energy [Formula: see text] for this complex are presented.

Investigation on the substituent effects of homodinuclear cobalt(II) complexes of tetraiminediphenol macrocycle on the synthesis of pure Co3O4 nanoparticles

Investigation on the substituent effects of homodinuclear cobalt(II) complexes of tetraiminediphenol macrocycle on the synthesis of pure Co3O4 nanoparticles

Liposomal Fe(III) Macrocyclic Complexes with Hydroxypropyl Pendants as MRI Probes.

Paramagnetic liposomes containing Fe(III) complexes were prepared by incorporation of mononuclear (Fe(L1) or Fe(L3)) or dinuclear (Fe2(L2)) coordination complexes of 1,4,7-triazacyclononane macrocycles containing 2-hydroxypropyl pendant groups. Two different types of paramagnetic liposomes were prepared. The first type, LipoA, has the mononuclear Fe(L1) complex loaded into the internal aqueous core. The second type, LipoB, has the amphiphilic Fe(L3) complex inserted into the liposomal bilayer and the internal aqueous core loaded with either Fe(L1) (LipoB1) or Fe2(L2) (LipoB2). LipoA enhances both T1 and T2 water proton relaxation rates. Treatment of LipoA with osmotic gradients to produce a nonspherical liposome produces a liposome with a chemical exchange saturation transfer effect as shown by an asymmetry analysis but only at high osmolarity. LipoB1, which contains an amphiphilic complex in the liposomal bilayer, produced a broadened Z-spectrum upon treatment of the liposome with osmotic gradients. The r1 relaxivity of LipoB1 and LipoB2 were higher than the r1 relaxivity of LipoA on a per Fe basis, suggesting an important contribution from the amphiphilic Fe(III) center. The r1 relaxivities of paramagnetic liposomes are relatively constant over a range of magnetic field strengths (1.4-9.4 T), with the ratio of r2/r1 substantially increasing at high field strengths. MRI studies of LipoB1 in mice showed prolonged contrast enhancement in blood compared to the clinically employed Gd(DOTA), which was injected at a 2-fold higher dose per metal than the Fe(III)-loaded liposomes.

Solid-State and Theoretical Investigations of Some Banister-Type Macrocycles with 2,2'-Aldoxime-1,1'-Biphenyl Units.

In the context of helical chirality, bridging of biphenyl units leads to banister-type compounds and the stability of the resulted atropisomers may increase dramatically if suitable changes are performed in the linker unit that coils around the biphenyl moiety. A rigorous density functional theory (DFT) study was conducted for macrocycles containing rigid oxime ether segments connected to the biphenyl backbone in order to determine how the rotation barriers are influenced by the presence of either a flexible oligoethyleneoxide or a more rigid m–xylylene component in the macrocycle. The calculated values for the racemization barrier were in good agreement with those obtained experimentally and confirm the benefit of introducing a more rigid unit in the macrocycle on the stability of atropisomers. Solid-state data were obtained and computed data were used to assess the contribution brought by supramolecular associations observed in the lattice to the stabilization of the crystal structure. Beside introducing rigidity in the linker, complexation of flexible macrocycles with alkali metal ions is also contributing to the stability of atropisomers, leading to values for the racemization barrier matching that of the rigid macrocycle. Using diethylammonium cation as guest for the macrocycle, a spectacular increase in the barrier to rotation was observed for the resulted pseudo[2]rotaxane.

Tetraaza macrocyclic Schiff base metal complexes bearing pendant groups: Synthesis, characterization and bioactivity studies

We report a new tetraaza macrocyclic Knoevenagel Schiff base as the 13-membered ligand developed by non-template route via condensation of 3-(cinnamyl)-pentane-2,4-dione with two equivalent of 4-aminoantipyrine as pendant group prior to its execution for Knoevenagel condensation with o-phenylenediamine. The above type of conjugate macrocyclic ligand tends to employ as a potential tetradentate ligand, which generated a seies of macrocyclic metal complexes (1–4) with Cu(II), Co(II), Ni(II) and Zn(II) metal ions. Herein, the macrocyclic ligand and its metal complexes were characterized by the spectral and analytical methods including UV–vis, FT-IR, 13C and 1H NMR, ESI-MS, EPR, microanalytical and magnetic moment values. The above set of data tend to suggest that synthesized metal complexes exist in square planar geometry, whereas high molar conductance values supported about the distribution of complexes in ionic nature. Indeed, cyclic voltammetry and optical absorption titration as well as hydrodynamic experiments and docking analysis data were used to identiy the way of binding of these metal complexes with calf thymus deoxyribonucleic acid as intercalation type. Further, DNA damage study was conducted by gel electrophoresis. Moreover, these complexes were studied for antimicrobial screening under in vitro condition against a set of microorganisms via broth dilution technique. It was noted that all the complexes occurred to reveal better activity as compared to macrocyclic Schiff base ligand. Also, the cancer cell lines including cervical, epithelioma, human breast and cell line of normal human dermal fibroblast were chosen to assess for cytotoxic effect with above samples.

Novel amide coupled phthalocyanines: Synthesis and structure-property relationship for electrocatalysis and sensing of hydroquinone

• Amide bridged CoPc macrocyclic dyes were prepared and elucidated the structure using physico-chemical techniques. • The amide CoPc was deposited on glassy carbon electrodeandcharacterized with SEM and electrochemical techniques. • Among different CoPcR 4 /GCE electrode, CoTAMFCAPc/GCE showed better sensitivity for QH 2 with lower LOD. • CoTAMFCAPc/GCE is stable and selective for QH 2 and has been applied for the detection of QH 2 in real samples. Analogs of amide bridge cobalt phthalocyanine complexes with different peripheral substituents have been prepared with good yield and these dyes possess dark green colour. These phthalocyanine complexes are characterized by elemental analysis, absorption spectra, infrared spectroscopy, mass and electrochemical methods. An attempt has been made to understand the structure–property relationship of these molecules for electrochemical properties. Hence, uniform and thin film of amide phthalocyanine ( Pc ) complex was administered on glassy carbon electrode (GCE) surface and scanning electron microscopy (SEM) images displayed the uniform distribution of the macrocycle on the surface. The modified electrodes are found to be electroactive and the Ohmic/Faradic surface response of the film is studied using electrochemical impedance spectroscopy (EIS). The formal Co(II)/(I) redox behavior of the substituted phthalocyanines have been explained using Hammett parameter. The electrode surface modified with terminal amide bridged Co-N4 macrocyclic complexes were applied for the sensing of hydroquinone (QH 2 ). An attempt was made to understand the influence of structure and functional groups on the electrocatalytic activity. Cyclic voltammetry (CV) displayed significantly increasing current trend for QH 2 in the quantitative range 200–2200 nM at the furan containing amide phthalocyanine (CoTAMFCAPc) electrode with a low limit of detection (LOD) of 65 nM. Further, the chronoamperometric analysis showed better linear response for QH 2 in 170–1530 nM range with LOD 56 nM at GCE/CoTAMFCAPc electrode compared to other molecules. The fabricated GCE/CoTAMFCAPc electrode demonstrated good stability and selectivity for QH 2 in presence of molecules with similar structure which co-exist along with QH 2 . GCE/CoTAMFCAPc electrode can be employed for practical application and produced superior recovery values for QH 2 .

Synthesis, crystal structure, and theoretical studies of a macrocyclic silver(I) complex of imino-pyridyl Schiff base ligand

The synthesis and characterization of an imino-pyridyl ligand N,N'-(butane-1,4-diyl)bis(1-(pyridin-2-yl)methanimine) (L) and its Ag(I)ClO4 complex (I) by various spectroscopic techniques and elemental analyses is presented in this study. X-ray single crystal structure of complex I revealed that in complex I, each Ag(I) ion is tetra coordinated with two pyridine N-atoms and two imine N-atoms of the ligand L, forming a macrocyclic dimeric Ag(I) grid. In the macrocyclic dimer complex I, Ag-Ag separation along the chain is 5.318 Å. The Ag-Npy average distance is 2.396 Å and that of the Ag-Nim is 2.257 Å. The macrocyclic dimer complex I is supramolecularly arranged by π-stacking interactions. Computational, Hirshfeld surface analysis and photophysical studies on ligand L and complex I have also been performed. Crystal data for C32H36Ag2Cl2N8O8 (M =947.33 g/mol): Triclinic, space group P-1 (no. 2), a = 9.1714(12) Å, b = 10.4373(14) Å, c = 10.8297(14) Å, α = 112.317(3)°, β = 91.391(3)°, γ = 92.353(3)°, V = 957.3(2) Å3, Z = 1, T = 293.15 K, μ(MoKα) = 1.220 mm-1, Dcalc = 1.643 g/cm3, 10248 reflections measured (4.07° ≤ 2Θ ≤ 53.098°), 3966 unique (Rint = 0.0280, Rsigma = 0.0331) which were used in all calculations. The final R1 was 0.0722 (I > 2σ(I)) and wR2 was 0.2229 (all data).

Chromium(III) Bis-alkynyl complexes supported by C-substituted cyclam MPC

Macrocyclic CrIII bis-alkynyl complexes have recently been used as a precursor in the synthesis of mono-alkynyl complexes, which can serve as synthetic intermediates towards the formation of dissymmetric bis-alkynyl complexes. The trans stereochemistry is essential to generate stable macrocyclic CrIII mono-alkynyl complexes, however, previously explored cyclam (1,4,8,11-tetraazacyclotetradecane) and its derivatives heavily favor the cis isomer after Cr insertion. The C-substituted cyclam MPC (5,12-dimethyl-7,14-diphenyl-1,4,8,11-tetraazacyclotetradecane) has shown a noteworthy preference towards the trans isomer upon insertion of Cr, making it desirable for the pursuit of dissymmetric bis-alkynyl complexes in significant quantity. Reported herein are the synthesis and characterization of trans-[Cr(MPC)(C2Ar)2]+ complexes, where Ar is Ph (1), Np (2), or C6H4tBu (3). Complexes 1 – 3 have structural and optical properties similar to previous CrIII bis-alkynyl complexes based on single-crystal X-ray diffraction, UV-vis and phosphorescence spectroscopical characterizations.

Enhancing the electrocatalytic activity of Fe phthalocyanines for the oxygen reduction reaction by the presence of axial ligands: Pyridine-functionalized single-walled carbon nanotubes

We have examined the electrocatalytic activity of iron phthalocyanine (FePc) and perchlorinated iron phthalocyanine 16(Cl)FePc for the oxygen reduction reaction (ORR) in alkaline medium with the two molecules either adsorbed on the external surface of single-wall carbon nanotubes (SWCNT) or covalently anchored via an axial pyridine ligand on pyridine-functionalized single-wall carbon nanotubes (py-SWCNT). Regardless of the particular phthalocyanine type, the ORR activity is higher when the substrate is py-SWCNT rather than SWCNT. The Tafel slopes for ORR are very similar for the two Fe macrocyclic complexes attached to SWCNTs in the two different configurations, suggesting a common rate-determining step for the ORR for all four catalysts. It is also observed that, for both the SWCNT and py-SWCNT supports, the ORR activity is higher for 16(Cl)FePc than for FePc. This is attributed to the electron-withdrawing effect of the peripheral and non-peripheral chlorine atoms in the macrocyclic ligand. While FeN4 macrocycles are known to be located on the strong binding side of a volcano correlation including several MN4 species, the chlorine substituents decrease the binding energy of O2 on the central Fe cation, thereby moving up the macrocycle catalyst towards the apex of the volcano correlation. Both the carbon surface and macrocyclic ligand effects were optimized with 16(Cl)FePc attached to py-SWCNT, which is more active than both FePc on SWCNT and FePc on py-SWCNT. Here we show that both the axial ligand and the electron withdrawing groups (-Cl) have a combined collaborative effect in increasing the catalytic activity for ORR of Fe-phthalocyanines confined on the external walls of single-wall carbon nanotubes.

Modular Synthesis of Tetraurea and Octaurea Macrocycles Encoded with Specific Monomer Sequences

Modular Synthesis of Tetraurea and Octaurea Macrocycles Encoded with Specific Monomer Sequences

Isolation and Identification of Pseudo Seven-Coordinate Ru(III) Intermediate Completing the Catalytic Cycle of Ru-bda Type of Water Oxidation Catalysts

Isolation and Identification of Pseudo Seven-Coordinate Ru(III) Intermediate Completing the Catalytic Cycle of Ru-bda Type of Water Oxidation Catalysts

Exploring Cyclic Aminopolycarboxylate Ligands for Sb(III) Complexation: PCTA and Its Derivatives as a Promising Solution.

In recent years Auger electron emitters have been suggested as promising candidates for radiotherapy with no side effects in cancer treatment. In this work we report a detailed coordination chemistry study of [Sb(PCTA)] (PCTA: 3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene-3,6,9-triacetic acid), a macrocyclic aminopolycarboxylate-type complex of antimony(III), whose 119Sb isotope could be a suitable low-energy electron emitter for radiotherapy. The thermodynamic stability of the chelate obtained by pH-potentiometry and UV-vis spectrophotometry is high enough (log K[Sb(PCTA)] = 23.2(1)) to prevent the hydrolysis of the metal ion near physiological pH. The formation of [Sb(PCTA)] is confirmed by NMR and electrospray ionization mass spectrometry measurements in solution; furthermore, the structure of [Sb(PCTA)]·NaCl·3H2O and [Sb(PCTA)]·HCl·3H2O is described by X-ray and density functional theory calculations. Consequently, the [Sb(PCTA)] is the first thermodynamically stable antimony(III) complex bearing polyamino-polycarboxylate macrocyclic platform. Our results demonstrate the potential of rigid (pyclen derivative) ligands as chelators for future applications of Sb(III) in a targeted radiotherapy based on the 119Sb isotope.