Diacetic Acid Research Articles

Clinical value of 68Ga-PSMA-11 PET/CT in the diagnosis of castration-resistant prostate cancer

Objective To assess the role of 68Ga-N, N′-bis(2-hydroxy-5-(carboxyethyl)benzyl) ethylenediamine-N, N′-diacetic acid(HBED-CC)-(Ahx)Lys-CO-Glu(PSMA-11) PET/CT on the detection of metastatic lesions from castration-resistant prostate cancer (CRPC). Methods Sixteen patients with CRPC who underwent 68Ga-PSMA-11 PET/CT between January 2015 and November 2015 were recruited in this study. Mean age of patients was (72±9) years. The PSA levels were 4-12 356 μg/L, Gleason score was 7-10. PET/CT was performed at 1 h postinjection of 68Ga-PSMA-11. Patient-based analysis and lesion-based analysis were performed. ROI analysis was used to calculate the tumor uptake (SUVmax). Final diagnosis was based on histopathology and results of other imaging examinations(99Tcm-MDP imaging, MRI). χ2 test was used to compare the diagnostic efficiencies of PET and CT. Results No adverse effects were observed in patients. 68Ga-PSMA-11 PET/CT showed moderate physiologic uptake in salivary glands and proximal small intestine, with predominant tracer clearance by the kidneys. All patients were positive on 68Ga-PSMA-11 PET/CT. Bone metastasis was found in 16 patients, liver metastasis in 2 patients (5 lesions), and lymph node metastasis in 4 patients (26 lesions). The SUVmax of liver, lymph node and bone metastases were 15.06±2.77, 7.54±5.20, 19.01±16.96, respectively. The diagnostic sensitivity, specificity and accuracy on bone metastasis with 68Ga-PSMA-11 PET and CT were 96.30%(52/54) vs 61.11%(33/54), 3/3 vs 1/3, 96.49%(55/57) vs 59.65%(34/57). The sensitivities and accuracies of the two modalities were significantly different(χ2=19.943, 22.593, both P<0.01). Conclusions 68Ga-PSMA-11 PET/CT could precisely detect both primary and metastatic lesions of CRPC, suggesting that it is of great value for the clinical management and treatment. Key words: Prostatic neoplasms, castration-resistant; Positron-emission tomography; Tomography, X-ray computed; Prostate-specific membrane antigen; Gallium radioisotopes

Metal Ion Complexes of N,N'-Bis(2-Pyridylmethyl)-trans-1,2-Diaminocyclohexane-N,N'-Diacetic Acid, H2bpcd: Lanthanide(III)-bpcd2- Cationic Complexes.

The synthesis and characterization of N,N'-bis(2-pyridylmethyl)-trans-1,2-diaminocyclohexane-N,N'-diacetic acid (H2bpcd) cationic complexes of La(III), Nd(III), and Sm(III) are reported. The Ln(III)-bpcd2- complex ions, where bpcd2- stands for N,N'-bis(2-pyridylmethyl)-trans-1,2-diaminocyclohexane-N,N'-diacetate, were isolated as PF6- salts. These salts were characterized by elemental analysis, X-ray crystallography, IR, and 1H and 13C NMR spectroscopy. Binuclear [La2(bpcd)2(H2O)2]2+ crystallized from an aqueous solution in the monoclinic P21/c space group as a cocrystallate with Na2bpcd and NaPF6, nominally Na2.34[La1.22(C22H26N4O4)2(H2O)2][PF6]2·2H2O, with a = 11.3343(6) Å, b = 17.7090(9) Å, c = 15.0567(8) Å, β = 110.632(3)°, and Z = 4 (Z' = 2). La is eight-coordinate with distorted dodecahedral coordination geometry provided by a N4O4 donor atom set. In addition to four N atoms from the bpcd2- ligand, La's coordination sphere includes O atoms from a water molecule and three acetate groups (one O atom from singly bound acetate and two O atoms from acetate groups that bridge the La centers). The 1H and 13C assignments for H2bpcd and the metal-bpcd2- complexes were made on the basis of 2D COSY and HSQC experiments, which established 1H-1H and 1H-13C correlations. The NMR spectral data were used to establish the symmetry of the cationic complexes present in aqueous solution. The data indicate that the La(III)-bpcd2- and Sm(III)-bpcd2- complexes are present in solution as a single species with C2 symmetry. The 1H NMR spectrum of [Nd(bpcd)]PF6 in D2O consists of eight considerably line-broadened, paramagnetic-shifted singlets. The ab initio quantum mechanical calculations at the PCM/MP2/SDD//HF/SDD level, which were established previously for determining isomerization energies for octahedral M(III)-bpad2- complex ions, were used to determine the relative free energies of the geometric isomers possible for eight- and nine-coordinate La(III)-bpcd2- cationic aqua complexes in aqueous solution, i.e., [La(bpcd)(H2O)2]+ and La(bpcd)(H2O)3]+.

Thermotropic MIDA Boronates as a Case Study for the Role of Dipolar Interactions in Liquid Crystalline Self-Assembly.

A series of MIDA (N-methylimino diacetic acid) boronates carrying 4-alkoxy, 3,4-bisalkoxy, or 3,4,5-trisalkoxyphenyl substituents were synthesized and their mesomorphic properties characterized by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction (XRD) techniques such as small- and wide-angle X-ray scattering (SAXS and WAXS, respectively). Most derivatives were liquid crystalline. In the case of mono- and bisalkoxy-substituted derivatives, C6 chains already induced smectic A (SmA) mesophases despite the bulky MIDA head group. With increasing chain length, columnar hexagonal (Colh ) phases replaced SmA phases in the disubstituted series. Quantum chemical calculations on a series of MIDA boronates show that the B-N bond is a dative bond with a positive charge on the boron atom and negative charges on the nitrogen and oxygen atoms. In addition, no π-interaction between the aryl moiety and B-N bond was found, thus the mesogenic unit is electronically decoupled from the MIDA head group. These theoretical findings were supported by IR and Raman spectra as well as by asingle crystal structure analysis of 4-ethoxyphenyl MIDA boronate. Calculations of the electrostatic potential of the MIDA boronate reveal a special polarity pattern that can support the formation of a two-dimensional network and is likely to explain the liquid crystalline self-assembly. The absence of any electronic cross-talk between the MIDA head group and B-aryl or B-alkyl substituents allows the efficient tailoring of the mesophase type through variation of the substituents.

Synthesis, structure, and complexing properties of 2,2′-{[(diisopropoxyphosphoryl)methyl]azanediyl}diacetic acid

2,2′-{[(Diisopropoxyphosphoryl)methyl]azanediyl}diacetic acid has been synthesized by the Kabachnik–Fields reaction and its complexing ability toward cobalt(II) and nickel(II) ions has been studied.

Radiochemistry and Preclinical PET Imaging of 68Ga-Desferrioxamine Radiotracers Targeting Prostate-Specific Membrane Antigen.

Radiotracers incorporating the urea-based Glu-NH-C(O)-NH-Lys group have gained prominence due to their role in targeting prostate-specific membrane antigen (PSMA)—a clinical biomarker of prostate cancer. Here, the synthesis, radiolabeling, and in vitro and in vivo characterization of two 68Ga-radiolabeled Glu-NH-C(O)-NH-Lys radiotracers conjugated to the desferrioxamine B (DFO) chelate were evaluated. Two linker groups based on amide bond and thiourea coupling chemistries were employed to develop 68Ga-DFO-Nsucc-PSMA (68Ga-4) and 68Ga-DFO-pNCS-Bn-PSMA (68Ga-7), respectively. Radiosynthesis proceeded quantitatively at room temperature with high radiochemical yields, chemical/radiochemical purities, and specific activities. Pharmacokinetic profiles of 68Ga-4 and 68Ga-7 were assessed using positron-emission tomography (PET) in mice bearing subcutaneous LNCaP tumors. Data were compared to the current clinical benchmark radiotracer 68Ga-HBED-CC-PSMA (68Ga-1) (HBED = N,N′-Bis(2-hydroxy-5-(ethylene-beta-carboxy)benzyl)ethylenediamine N,N′-diacetic acid). Results indicated that the target binding affinity, protein association, blood pool and background organ clearance properties, and uptake in PSMA-positive lesions are strongly dependent on the nature of the chelate, the linker, and the spacer groups. Protein dissociation constants (K d values) were found to be predictive of pharmacokinetics in vivo. Compared to 68Ga-1, 68Ga-4 and 68Ga-7 resulted in decreased tumor uptake but enhanced blood pool clearance and reduced residence time in the kidney. The study highlights the importance of maximizing protein binding affinity during radiotracer optimization.

68Ga-Chelation and comparative evaluation of N,N'-bis-[2-hydroxy-5-(carboxyethyl)benzyl]ethylenediamine-N,N'-diacetic acid (HBED-CC) conjugated NGR and RGD peptides as tumor targeted molecular imaging probes.

Peptides containing RGD and NGR motifs display high affinity towards tumor vasculature molecular markers, integrin αvβ3 and CD13 receptors, respectively. In the present study, RGD and NGR peptides were conjugated with the novel acyclic chelator N,N'-bis-[2-hydroxy-5-(carboxyethyl)benzyl]ethylenediamine-N,N'-diacetic acid (HBED-CC) for radiolabeling with 68Ga. The radiotracers [68Ga-HBED-CC-c(NGR)] and [68Ga-HBED-CC-c(RGD)] were quite hydrophilic with respective log P values being -2.8 ± 0.14 and -2.1 ± 0.17. 68Ga-HBED-CC-c(RGD) displayed a significantly higher (p < 0.05) uptake in murine melanoma B16F10 tumors as compared to 68Ga-HBED-CC-c(NGR) indicating its higher specificity towards integrin αvβ3-positive tumors. The two radiotracers showed similar uptake in CD13-positive human fibrosarcoma HT-1080 tumor xenografts (∼1.5 ± 0.2% ID g-1). The tumor uptake of the two radiotracers was significantly reduced (p < 0.05) in both animal models during blocking studies. The tumor-to-blood ratio was observed to be ∼2-2.5 for the two radiotracers, whereas the tumor-to-muscle ratio was significantly higher (p < 0.005) for 68Ga-HBED-CC-c(RGD) in the two animal models. The two radiotracers 68Ga-HBED-CC-c(NGR) and 68Ga-HBED-CC-c(RGD) exhibited renal excretion with rapid clearance from blood and other non-target organs. Thus, 68Ga-chelated HBED-CC conjugated NGR and RGD peptides expressed features conducive towards development as tumor targeted molecular imaging probes. This study further opens avenues for the successful conjugation of different peptides with the acyclic chelator HBED-CC and expansion of 68Ga-based radiopharmaceuticals.

Definition of the Labile Capping Bond Effect in Lanthanide Complexes.

Two macrocyclic ligands containing a cyclen unit, a methyl group, a picolinate arm, and two acetate pendant arms attached to two nitrogen atoms of the macrocycle either in trans (1,7-H3 Medo2 ampa = 2,2'-(7-((6-carboxypyridin-2-yl)methyl)-10-methyl-1,4,7,10-tetraazacyclododecane-1,4-diyl)diacetic acid) or in cis (1,4-H3 Medo2 ampa) positions are reported. These ligands provide eight-coordination to the Ln3+ ions, leaving a coordination position available for a water molecule that occupies a capping position in the twisted square antiprismatic polyhedron (1,4-H3 Medo2 ampa) or one of the positions of the square antiprism (1,7-H3 Medo2 ampa). The charge neutral [Gd(1,7-Medo2 ampa)] complex presents an unprecedentedly low water-exchange rate (kex298 =8.8×103 s-1 ), whereas water exchange in [Gd(1,4-Medo2 ampa)] is three orders of magnitude faster (kex298 =6.6×106 s-1 ). These results showcase the labile capping bond phenomenon: A ligand occupying a capping position is hindered by the environment and thus is intrinsically labile.

Synthesis, Characterization and evaluation of new

ABSTRACT A new polymer surfactant derived from cis-1,4-cyclohexane bis(methylamine) and ethylenediamintetraacetic acid [2,2'-(1,12-bis(4-(aminomethyl)cyclohexyl)-3,10-dioxo-2,5,8,11-tetraazadodecane-5,8-diyl) diacetic acid ] was synthesized and characterized by FTIR and 1HNMR. A series of electrochemical measurements, including corrosion potential and corrosion current has been made on the surfactant for carbon steel samples in corrosive environment. Results showed that the surfactant can offer some degrees of protection in the corrosive environments. The corrosion study of this polymer outline that it have a good resistant to the corrosion of carbon steel in 0.1 M solution of HCl, which can be indicate to uses as anti-corrosion materials

Synthesis and Properties of a Novel 3D Europium Coordination Polymer with Helical Chain and (3,6)‐Connected rtl Net

AbstractThe first coordination polymer of 2,2′‐((4‐carboxymethyl‐1,3‐phenylene)bis(oxy)) diacetic acid (H3L) with europium(III) ion, [Eu(L)(H2O)]·3H2O (1), has been hydrothermally synthesized and structurally characterized. Complex 1 exhibits a 3D coordination polymer with helical chain and rtl topology of the point symbol (4·62)2(42·610·83) based on [Eu2(COO)4] as secondary building unit (SBU). Furthermore, the luminescent and magnetic properties of complex 1 are studied.

New lanthanide biphenyl-4,4′-diacetates − hydrothermal synthesis, spectroscopic, magnetic and thermal investigations

The hydrothermal reaction of lanthanide chlorides and sodium salt of biphenyl-4,4′-diacetic acid (H2bpda) yielded a series of coordination polymers of the general formula Ln2(bpda)3·nH2O (Ln=lanthanide ions(III) except for Pm(III), n=3–7). Single-crystal and powder X-ray diffraction analyses revealed that complexes form three-dimensional coordination networks. Tetradentate biphenyl-4,4′-diacetate ligand coordinates Ln(III) through both bidentate-chelating carboxylate groups. Their thermal behaviours was investigated by the TG-DSC and TG-FTIR methods. The influence of atmosphere of heating on thermal stability of complexes was also examined. Magnetic studies of neodymium and praseodymium complexes showed weakly antiferromagnetic exchange interactions between lanthanide ions.

Use of product and ingredient tools to assess the environmental profile of automatic dishwashing detergents

Sustainable use of resources is gaining more attention as demonstrated into recent policy goals by the United Nations and the European Union and becomes an integral part of many corporate sustainability visions. The case study shows the more efficient use of materials in P&G automatic dishwashing detergents (ADD) placed on the market in Europe, Middle East and Africa (EMEA) by replacing sodium tripolyphosphate (STPP) with methyl glycine diacetic acid (MGDA). The use of phosphates in ADD in the European Union will be restricted as of 2017. This study is innovative as it combines several tools in a complementary way to enable data based decision making. Life Cycle Assessment (LCA) consistent with ISO 14040/44 standards compares environmental impacts for two ADD unit dose products (i.e. with and without STPP). Different assessment tools were used to evaluate the freshwater aquatic toxicity profile: the Critical Dilution Volume (CDV), USEtox, environmental risk assessment and the Environmental Safety Check (ESC).For the relevant LCA indicators, a significant reduction (i.e. > 10%) is observed on ADD products without phosphate versus the phosphate containing product. CDV and USEtox scores on the down the drain emissions from the new product are reduced by 30% and 22% respectively as compared to the phosphate containing formula. Overall, no major trade-offs are observed with the replacement of STPP by MGDA. Benefits are due to a 20% reduction of the mass of ingredients per dose with the new product and the replacement of STPP by MGDA. The ESC evaluation and environmental risk assessment for MGDA show that a low environmental risk is expected per its favorable environmental fate and ecotoxicological profiles. Based on the proven safety profile of MGDA, the reductions in LCA indicators and absence of trade-offs, it can be concluded that the new product has an improved environmental profile.

Biotinidase Resistant 68Gallium-Radioligand Based on Biotin/Avidin Interaction for Pretargeting: Synthesis and Preclinical Evaluation.

A new macrocyclic system 2,2'-(12-amino-11,13-dioxo-1,4,7,10-tetraazacyclotridecane-4,7-diyl)diacetic acid (ATRIDAT) was designed for coordinating metals in +2 and +3 oxidation states particularly 68Ga(III), for PET imaging. ATRIDAT was conjugated to d-biotin for pretargeting via biotin-avidin interaction. This model provides high tumor targeting efficiency and stability to biotinidase activity leading to modest signal amplification at the tumor site. Cyclization of triethylenetetramine with protected diethylamino malonate resulted in the formation of 13 membered diamide ring. d-Biotin was then anchored on the pendant amine rendering α-methyne carbon to the biotinamide bond which blocks the biotinidase enzyme activity. Biotinidase stability assay showed remarkable stability toward the action of biotinidase with ∼95% remaining intact after treatment following 4 h. Binding affinity experiments such as HABA assay, competitive displacement studies with d-biotin and CD showed high binding affinity of the molecule with avidin in nanomolar range. Biotin conjugate was successfully radiolabeled with 68Ga(III) with radiolabeling efficiency of ∼70% and then purified to get 99.9% radiochemical yield. IC50 of the compound was found to be 2.36 mM in HEK cell line and 0.82 mM in A549 as assessed in MTT assay. In biodistribution studies, the major route of excretion was found to be renal. Significant uptake of 4.15 ± 0.35% was observed in tumor in the avidin pretreated mouse at 1 h. μPET images also showed a high tumor to muscle ratio of 26.8 and tumor to kidney ratio of 1.74 at 1 h post-injection after avidin treatment.

Synthesis of glycinamides using protease immobilized magnetic nanoparticles

In the present investigation, Bacillus subtilis was isolated from slaughterhouse waste and screened for the production of protease enzyme. The purified protease was successfully immobilized on magnetic nanoparticles (MNPs) and used for the synthesis of series of glycinamides. The binding and thermal stability of protease on MNPs was confirmed by FTIR spectroscopy and TGA analysis. The surface morphology of MNPs before and after protease immobilization was carried out using SEM analysis. XRD pattern revealed no phase change in MNPs after enzyme immobilization. The processing parameters for glycinamides synthesis viz. temperature, pH, and time were optimized using Response Surface Methodology (RSM) by using Design Expert (9.0.6.2). The maximum yield of various amides 2 butyramidoacetic acid (AMD-1,83.4%), 2-benzamidoacetic acid (AMD-2,80.5%) and 2,2′((carboxymethyl) amino)-2-oxoethyl)-2-hydroxysuccinyl)bis(azanediyl))diacetic acid (AMD-3,80.8%) formed was observed at pH-8, 50°C and 30min. The synthesized immobilized protease retained 70% of the initial activity even after 8 cycles of reuse.

Coordination Architectures of energetic Cd (II) coordination polymers constructed by the bifunctional substituted-tetrazole-carboxylate ligands

Three different tetrazole-carboxylate ligands, monotetrazole-carboxylate H2tza (H2tza=1,5-tetrazole-diacetic acid), Hpztza (Hpztza=5-(2-pyrazinyl)tetrazole-2(1-methyl)acetic acid), ditetrazole-carboxylate H2tzpha (H2tzpha=1,3-di(tetrazole-5-yl)benzene-N2,N2′-diacetic acid) have been chosen to react with CdCl2·6H2O, resulting in the formation of three new compounds [Cd2(tza)2] (1), [Cd(pztza)2] (2) and [Cd(tzpha)(CH3OH)2] (3). The coordinate sites of the three ligands are major influenced by the different substituted group of tetrazole ring. These compounds have been characterized by elemental analysis, IR and single crystal X-ray diffraction. Compound 1 displays a complex 3D structure; compound 2 shows a 3D network and compound 3 features a 2D layer network. Furthermore, the luminescence properties investigated at room temperature in the solid state showed excellent ligand-centered luminescence. The obvious enhancement in luminescence makes these compounds potential materials for optical use. The differential scanning calorimetry (DSC) and thermogravimetric-differential thermogravimetric (TG-DTG) analyses were applied to evaluate the thermal decomposition behavior of such compounds, showing that compounds 2 and 3 can be used as potential energetic materials. The relevant thermodynamic parameters ΔH, ΔS and ΔG were calculated as well.

Evaluating the Chemical Reaction of Chelating Agents with Xanthan Gum

Xanthan gum is a polysaccharide natural polymer that is used heavily as a viscosifier in oil and gas industry especially with fracturing and gravel pack fluids. Numerous additives are required to control the properties of the fracturing and gravel pack fluids such as biocides, clay stabilizers, and some other additives to maintain the viscosity at high temperature during the fracturing operations. These additives have their limitations, and they will increase the cost of the operation. The objective of this research is to evaluate the chemical reaction of xanthan gum with different chelating agents [ethylenediaminetetraacetic acid (EDTA), glutamic acid diacetic acid (GLDA), and diethylenetriaminepentaacetic acid (DTPA)] at different conditions of pH, concentrations, temperature, and time to determine the optimum conditions for removing the polymer filter cake after fracturing and gravel pack operations . The results obtained showed that mixing chelating agents (DTPA, EDTA, and GLDA) with xanthan gum had a big effect of increasing the viscosity of the solution. DTPA and EDTA at different pH and shear rates over long time (36 h) did not break the XC-polymer solution at \(200~^{\circ }\hbox {F}\). GLDA (20 wt%, pH 12) increased the viscosity of the xanthan gum solution from 33 to 45 cP for 11 h at \(200~^{\circ }\hbox {F}\) and a shear rate of \(170.3\, \hbox {S}^{-1}\). Under the same conditions, GLDA worked as a breaker after 11 h as the apparent viscosity of the GLDA-XC solution was decreased from 45 cP to 11 and 3 cP after 24 and 36 h, respectively. The optimum concentration of GLDA was found to be 20 wt%, and the optimum pH was found to be 12.

Design and synthesis of fluorescent reagents for selective detection of dopamine

I report the development of (E)-2,2′-(5-(2-(4-(dicyanomethylene)-6-methyl-4H-pyran-2-yl)vinyl)-2-hydroxy benzylazanediyl)diacetic acid Fe(II) complex (1-Fe2+), a fluorescent reagent that can be used to detect dopamine. 1-Fe2+ was constructed using the cyanopyranyl group as the fluorophore and an Fe2+ complex both as the ligand exchange site and fluorescence quenching moiety. In contrast to the weak fluorescence emission of 1-Fe2+ in the absence of dopamine, a much stronger fluorescence emission was observed following the addition of dopamine owing to the release of Fe2+ from compound 1, which indicates significant fluorescence enhancement and the binding of Fe2+ to dopamine. The fluorescence intensities of the reagent were plotted as a function of the dopamine concentration and a good linear relationship was observed. The reaction of 1-Fe2+ with dopamine was not affected by the presence of foreign substances, thereby allowing for the highly selective detection of dopamine. The experimental results clearly showed that 1-Fe2+ is a good dopamine indicator, and it can be widely employed in dopamine detection protocols.

Two new Cd(II) coordination polymers based on 1-(imidazo-1-ly)-4-(1,2,4-triazol-1-ylmethyl)benzene and dicarboxylate ligands: Syntheses, crystal structures, and luminescent properties

ABSTRACT Two new Cd(II) coordination polymers, {[Cd(IPA)(TMB)]·0.5(H2O)}n (1)and [Cd(PDA) (TMB)]n(2) [TMB = 1-(imidazo-1-ly)-4-(1,2,4-triazol-1ylmethyl)benzene, H2IPA = 5-nitroisophthalic acid and H2PDA = 1,4-Phenylene diacetic acid] have been synthesized and structurally characterized. The structure determination reveals that complex 1 displays a one-dimensional (1D) chain, complex 2 features a two-dimensional (2D) layer structure, and complex 3 shows a three-dimensional (3D) framework with twofold interpenetrated pcu topology. The structural differences indicate that the backbones of the dicarboxylate acids are an important key to form the final coordination polymers. Furthermore, the photoluminescent properties of complexes 1–3 were investigated in the solid state at room temperature.

Physico-chemical properties of MnII complexes formed with cis- and trans-DO2A: thermodynamic, electrochemical and kinetic studies

Synopsis: MnII complexes formed with cis- and trans-DO2A (DO2A=1,4,7,10-tetraazacyclododecane-1,4 (or 1,7) -diacetic acid) chelators were investigated by pH-potentiometry, 1H relaxometry, UV-vis spectrophotometry and cyclic voltammetry. The physico-chemical characteristics of MnII complexes of these structure isomers do not differ dramatically, however the cis-DO2A platform has better potential for further development.Manganese (MnII) is a promising alternative to gadolinium (GdIII) as a magnetic resonance imaging (MRI) agent. Unlike gadolinium, this biogenic metal might be better tolerated by the body, reducing the risk of toxicity associated with dissociation of the complex. Herein we report detailed equilibrium and kinetic studies performed with MnII complexes of 1,4,7,10-tetraazacyclododecane-1,4-diacetic acid (1,4-DO2A or cis-DO2A) and 1,4,7,10-tetraazacyclododecane-1,7-diacetic acid (1,7-DO2A or trans-DO2A). The protonation constants of the ligands as well as stability constants of their MnII complexes have been determined by pH-potentiometry. The stability constants of [Mn(cis-DO2A)] are slightly higher than those of [Mn(trans-DO2A)] (log KMnL=15.68 and 15.22, respectively). Cyclic voltammetric (CV) experiments performed on [Mn(cis-DO2A)] and [Mn(trans-DO2A)] revealed quasireversible systems with a half-wave potential of +636 and +705mV versus Ag/AgCl, respectively. These values indicate that the MnII ion in these complexes is more stabilized against the oxidation than in [Mn(EDTA)]2−. The kinetic inertness of the complexes has been studied in transmetallation reactions with CuII or ZnII ions. Kinetic measurements indicate that both MnII complexes primarily undergo acid catalyzed dissociation and positions of the acetate pendant arms do not influence kinetic inertness. The inertness of these complexes is comparable to that of [Mn(NOTA)]− (NOTA=1,4,7-triazacyclononane-1,4,7-triacetic acid) and about twenty times lower than that of [Mn(DOTA)]2− (DOTA=1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid). In conclusion, [Mn(cis-DO2A)] displays some very interesting features (thermodynamic and redox stability as well as kinetic inertness) which makes this complex a promising platform for the development of more efficient MnII complexes as alternatives to Gd-based MRI agents.

Two SrII coordination compounds based on tetrazole-carboxylate ligands

Abstract Two novel coordination compounds, [Sr(atzp)2(H2O)2]·CH3OH (1) and [Sr(dtzpha)(H2O)3]·4H2O (2) [Hatzp=5-aminotetrazole-1-propionic acid, H2dtzpha=1,3-di(tetrazol-5-yl)benzene-N2,N2′-diacetic acid)], have been generated by using 5-aminotetrazole-1-propionic acid and 1,3-di(tetrazol-5-yl)benzene-N2,N2′-diacetic acid to react with strontium salts, respectively. X-ray diffraction analysis reveals that carboxylic groups of two ligands show the same coordination mode (the μ 1,1,3-COO coordination mode), compound 1 displays a 1D structure while compound 2 shows a 2D structure, which implies the influence of the number of the carboxylic acid groups. Luminescence properties of 1 and 2 were investigated at room temperature in the solid state.

Comparative biological evaluation between 99mTc(CO)3 and 99mTc-Sn (II) complexes of novel quinoline derivative: a promising infection radiotracer

A novel quinoline derivative, 2,2′-[(5-chloro-8-hydroxyquinoline-7-yl) methylazanediyl] diacetic acid (CHQMADA) was labeled with 99mTc using SnCl2·2H2O as a reducing agent to give a complex with a labeling yield 94 %. Also [99mTc(H2O)3(CO)3]+ was prepared by heating at 100 °C for 30 min using 2 mg CHQMADA at pH 8 to give a labeling yield >99 %. 99mTc-(CO)3 CHQMADA and 99mTc-Sn(II)-CHQMADA showed tissue uptake (target to non target T/NT = 6.80 ± 0.22) and (T/NT = 5.65 ± 0.34) respectively in Escherichia coli induced infection, which is higher than the commercially available 99mTc-ciprofloxacin (T/NT = 3.80 ± 0.80). In conclusion, both complexes were able to differentiate between septic and aseptic inflammation with superiority of [99mTc-(CO)3 CHQMADA].