Search

The crystal structure of the title compound, [Ni(C8H20N4)(NO3)]NO3, at room temperature, has monoclinic (P21/n) symmetry. The structure displays inter-molecular hydrogen bonding. The nickel displays a distorted bipyramidal geometry with the symmetric bidentate bonded nitrate occupying an equatorial site. The 1,4,7,10-tetraazacyclododecane (cyclen) backbone has the [4,8] configuration, with three nitrogen-bound H atoms directed above the plane of the nitrogen atoms towards the offset nickel atom with the fourth nitrogen-bound hydrogen directed below from the plane of the nitrogen atoms. The nitrate anion O atoms are seen to hydrogen bond to the H atoms bound to the N atoms of the ligand. [ABSTRACT FROM AUTHOR]

The crystal structure of the title compound, [Ni(C8H20N4)(NO3)]NO3, at room temperature, has monoclinic (P21/n) symmetry. The structure displays intermolecular hydrogen bonding. The nickel displays a distorted bipyramidal geometry with the symmetric bidentate bonded nitrate occupying an equatorial site. The 1,4,7,10-tetraazacyclododecane (cyclen) backbone has the [4,8] configuration, with three nitrogen-bound H atoms directed above the plane of the nitrogen atoms towards the offset nickel atom with the fourth nitrogen-bound hydrogen directed below from the plane of the nitrogen atoms. The nitrate anion O atoms are seen to hydrogen bond to the H atoms bound to the N atoms of the ligand.

In the title salt, [ZnCl(C23H30N4)]NO3, the central ZnII atom of the complex cation is coordinated in a square-pyramidal arrangement by four nitrogen atoms from cyclen (1,4,7,10-tetraazacyclododecane) in the basal plane and one chlorido ligand in the apical position. The anthracene group attached to cyclen contributes to the crystal packing through intermolecular T-shaped π interactions. Additionally, the nitrate anion participates in intermolecular N—H...O hydrogen bonds with cyclen.

Tris(tetra-armed cyclen) with three cyclens linearly linked (1a) and pentakis(tetra-armed cyclen) with four cyclens linked to the central cyclen (1b) have been prepared. These structures of the ligands were confirmed by 1H and 13C{1H} NMR, CSI-MS, and elemental analysis. Upon addition of Ag+ to these novel ligands, we observed the formation of 1:1 to 1:3 (= 1a:Ag+) complexes and 1:1 to 1:5 (= 1b:Ag+) complexes, respectively, according to stoichiometry. The association constants for 1a and 1b with Ag+ using titration experiments with UV–vis spectroscopy were also estimated. Logβ1, logβ2, and logβ3 of 1a were 6.4, 14, and 21, respectively, while logβ1, logβ2, logβ3, logβ4, and logβ5 of 1b were 6.8, 13, 19, 24, and 29, respectively. The association constants obtained from experiments revealed that all cyclen units within the molecules formed complexes with Ag+ that exhibited nearly identical association constants. The result suggests that the ligands have a uniform binding affinity for Ag+ throughout their structures. [ABSTRACT FROM AUTHOR]

In the title dinuclear CuII complex, [Cu2(NO3)(C24H46N8)(H2O)](NO3)3·3H2O, the two CuII molecules both have a square-pyramidal geometry, but the ligands in the axial positions are different: a water molecule and a nitrate ion. All nitrate ions, water molecules, and N—H groups are involved in an intermolecular hydrogen-bond network.

• [Ni(cyclen)(H 2 O) 2 ] 2 [(AsO) 6 (NiMo 6 O 24)]·3H 2 O (abbreviated as NiAM, cyclen = 1,4,7,10-tetrazacyclododecane) represents the first cyclen-Ni functional polymolybdate. • The synthetic method of NiAM will serve as a good example for subsequent synthesis and formation of such cluster containing POMs. • NiAM can catalyze the production of reactive oxygen species (ROS) in water efficiently. The reactive oxygen species (ROS), serving as a crucial biochemical reaction medium, is intricately involved in a myriad of physiological and pathological processes. The proper use of ROS can solve many practical problems, for example killing harmful microorganisms or cells, removing pollutants in water, etc. Therefore, the design and synthesis of artificial oxidase with catalytic activity in producing ROS become a hot research spot from bio-inorganic chemistry to catalytic industry. Herein, a cyclen-nickel complex functionalized polymolybdate, [Ni(cyclen)(H 2 O) 2 ] 2 [(AsO) 6 (NiMo 6 O 24)]·3H 2 O (abbreviated as NiAM, cyclen = 1,4,7,10-tetrazacyclododecane), which can acting as a catalyzed oxidase to generating ROS, has been structurally characterized by means of single-crystal X-ray diffraction (SXRD), elemental analyses, IR and UV– vis spectra, powder X-ray diffraction (PXRD), and bond valence sums (Σ s) calculation. The NiAM's principal element, as revealed by SXRD, indicates that it is an ionic complex that composed by two [Ni(cyclen)(H 2 O) 2 ]2+and one modified Anderson-type cluster [(AsO) 6 (NiMo 6 O 24)]4–. Interestingly, NiAM possesses effective ability in catalyzing the ROS generation in aqueous solution. As a result, it can remove methylene blue (MB) dyes from the stable solution system. [ABSTRACT FROM AUTHOR]

Incorporation of nanosized metal organic frameworks (MOFs) fillers into polyamide layer can essentially enhance the performance of thin film nanocomposite (TFN). However, in situ growth of MOFs during interfacial polymerization (IP) is impeded by the insolubility of metal precursors in alkaline aqueous solutions. Herein, 1,4,7,10-tetraazacyclododecane (Cyclen), a macrocyclic polyamine capable of complexing metal ions, was integrated into the IP process to fabricate TFN membranes with in situ synthesized zeolitic imidazolate framework-8 (ZIF-8). Compared to the conventional piperazine-trimesoyl chloride (PIP-TMC) membrane, the modified PIP + Cyclen-TMC membrane features a thinner and denser polyamide layer. After the incorporation of ZIF-8, the polyamide layer becomes looser, more hydrophilic and electronegative. The resultant TFN membranes demonstrated exceptional water permeance (31.4 L m−2 h−1 bar−1) and improved selectivity (96.3 %), signifying a permeance enhancement of 182.6 % compared with that of the pristine PIP-TMC membrane. Additionally, the optimized membrane manifested enhanced fouling resistance and long-term stability. This macrocyclic polyamines mediated in situ growth technique can be extended to other combinations of macrocyclic polyamines and metal precursors, offering a novel paradigm for the fabrication of TFN-MOFs membranes for desalination. [Display omitted] • Macrocyclic polyamines were used to mediate the growth of MOFs during interfacial polymerization. • The introduction of macrocyclic polyamines (Cyclen) can effectively regulate the formation of polyamide layer. • In situ formed nanosized ZIF-8 were well dispersed into polyamide layer through the complexation between zinc and Cyclen. • The optimized membrane exhibited superior water permeance (31.4 L m−2 h−1 bar−1) and improved Na 2 SO 4 rejection (96.3 %). [ABSTRACT FROM AUTHOR]

Wormlike micelles, which are linear aggregates created by the self-assembly of surfactants, may entangle to form dynamic three-dimensional network-like structures, endowing solutions with considerable macroscopic viscoelasticity. Recently, a pressing need has arisen to research a novel stimuli-responsive worm-like micelle that is efficient and environmentally friendly. CO2 is an inexpensive, abundant, non-toxic, biocompatible, and non-combustible gas, and it is anticipated that CO2 may serve as the trigger for stimuli-responsive worm-like micelles. In this paper, the formation of CO2-switchable pseudo-tetrameric surfactants, which subsequently self-assemble into CO2-switched wormlike micelles, is accomplished using a simple mixing of two commercial reagents, such as stearic acids and cyclen. The rheological characteristics switched by the use of CO2 are cycled between that of a low-viscosity (1.2 mPa·s) fluid and a viscoelastic fluid (worm-like micelles, 3000 mPa·s). This article expands the field of study on stimuli-responsive worm-like micelles. [ABSTRACT FROM AUTHOR]

Organic solvent nanofiltration (OSN) technology has the potential to separate and purify organic solvents in high efficiency. The self-supporting structure and ease scaling-up merit of hollow fiber (HF) type membrane make it an attractive option for OSN application. Nevertheless, low solvent permeance is one of technical limitation in conventional HF OSN membranes due to their excessively dense separation layer and limited free volume. Herein, we propose a straightforward methodology to fabricate HF thin-film composite (TFC) OSN membranes having exceptional solvent permeance and solute rejection. This methodology is conducted through the incorporation of macrocyclic molecules, 1,4,7,10-tetraazacyclododecane (Cyclen), into the aqueous monomer solution of m -Phenylenediamine (MPD) during the interfacial polymerization to modulate the separation layer. In this way, the average pore size of the separation layer could be precisely enlarged and narrowed on a sub-nanometer scale. Consequently, the Cyclen-modulated HF TFC OSN membrane exhibits excellent separation performance, with a pure methanol permeance of 76.7 L m−2 h−1 MPa−1 and a pure ethanol permeance of 26.5 L m−2 h−1 MPa−1, which is nearly 60 % increase compared with the baseline TFC membrane, while the Rhodamine B (RDB) rejection only shows a neglectable decrease from 99.7 % to 99.6 % at optimal fabrication conditions. Furthermore, the optimal membrane exhibits remarkable solvent resistance, withstanding a 35 d immersion in N, N -dimethylformamide (DMF) at room temperature without a significant decline in RDB rejection. Additionally, the optimal membrane shows higher than 99 % rejection for Rifampicin (823 Da), which is considerable potential for applications in the separation and recovery of pharmaceuticals. In summary, incorporating macrocyclic polyamine Cyclen into the polyamide layer is a viable method for regulating the physical structure and strengthening the performance of HF OSN membrane. [Display omitted] • Hollow fiber OSN membrane doped with macrocyclic polyamine Cyclen. • The incorporation of Cyclen results in an enlarged average pore size. • Ethanol permeance increases nearly 60 % with Rhodamine B rejection of 99.6 %. • No significant decrease in Rhodamine B rejection during 35 d immersion in DMF. [ABSTRACT FROM AUTHOR]

[Display omitted] • Different surfactants precisely regulate the diffusion rate of Cyclen monomer. • TFC membranes with different surfactants have customized pore size distributions. • TFC membrane enables on-demand desalting and antibiotic/salt separation. • TFC membrane has great application potential in antibiotic/salt separation. The diffusion of amine monomer during interfacial polymerization (IP) directly affects the structure and properties of the polyamide (PA) separation layer. Surfactants can regulate the diffusion rate of monomers and change the microstructure of the PA layer. In this study, a PA nanofiltration (NF) membrane with the tailor-made pore size is fabricated by modulating the diffusion rate of 1, 4, 7, 10-tetraazacyclododecane (Cyclen). Surfactants with different alkyl chain lengths are used to precisely regulate the diffusion rate of Cyclen monomer. The longer the alkyl chain length of the surfactant is, the faster the diffusion rate of the Cyclen monomer is, resulting in the formation of a PA layer with a narrow pore size distribution. The prepared composite membrane is qualified for on-demand desalting and antibiotic/salt separation performance by changing the length of the alkyl chain. For example, surfactants with short alkane chains (C 4) endow the NF membranes with a high water permeance of 30.7 L−1 m−2h−1 bar−1 for tetracycline separation. Surfactants with long alkane chains (C 12) endow the NF membranes with a high selectivity of 84.8 for tetracycline/NaCl separation. This study provides further evidence for surfactant-regulated IP reactions and offers new ideas for the tailor-made regulation of NF membrane properties. [ABSTRACT FROM AUTHOR]

Abstract Background Lead-212 (212Pb, t1/2 = 10.6 h) and lead-203 (203Pb, t1/2 = 51.9 h) are an element-equivalent, or a matched theranostic radioisotope pair that show great potential for application in targeted radionuclide therapy (TRT) and single-photon emission computed tomography (SPECT), respectively. At TRIUMF we have produced both 203Pb and 212Pb using TRIUMF’s TR13 (13 MeV) and 500 MeV cyclotrons, and subsequently purified and evaluated both radioisotopes using a series of pyridine-modified DOTA analogues in comparison to the commercially available chelates DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) and TCMC (1,4,7,10-tetraaza-1,4,7,10-tetra(2-carbamoylmethyl)cyclododecane). Results Proton irradiation (12.8 MeV) of natural and enriched thallium-203 (203Tl) targets gave 203Pb saturation yields of 134 ± 25 and 483 ± 3 MBq/μA, respectively. Thorium-228 (228Th, t1/2 = 1.9 y), a by-product of 232Th proton spallation on TRIUMF’s main 500 MeV beamline (beamline 1A, BL1A), was recovered to build a 228Th/212Pb generator with the ability to deliver up to 9–10 MBq of 212Pb daily. Both lead isotopes were purified via solid phase extraction chromatography (Pb resin), and isolated in an acetate form ([203/212Pb]Pb(OAc)2) suitable for direct radiolabeling of chelators and bioconjugates. A series of cyclen-based chelators (herein referred to as DOTA-1Py, -2Py, and -3Py) along with established chelates DOTA and TCMC were evaluated for their ability to complex both 203Pb and 212Pb. All chelates incorporated 212Pb/203Pb efficiently, with higher radiolabeling yields observed for the 212Pb-complexes. Conclusion The production of 203Pb and 212Pb was established using TRIUMF 13 MeV and 500 MeV cyclotrons, respectively. Both production methods provided radiometals suitable for subsequent radiolabeling reactions using known and novel chelates. Furthermore, the novel chelate DOTA-3Py may be a good candidate for biomolecule conjugation and further theranostic 212Pb/203Pb studies.

Objectives. Chlorin and bacteriochlorin photosensitizers are effective agents for cancer photodynamic therapy and fluorescence imaging. They are also excellent chelators forming stable metal complexes. Besides, 64Cu and 109Pd isotopes can serve as emitters for nuclear medicine. Chelation of these metals with cyclen conjugates with chlorin and bacteriochlorin photosensitizers can become a simple and universal strategy for the synthesis of diagnostic and therapeutic radiopharmaceuticals for nuclear medicine. This article reports on the synthesis of similar Cu and Pd complexes of cyclen conjugates with pheophorbide and bacteriopheophorbide and the study of their photophysical properties.Methods. Metalation of cyclen conjugates was carried out with palladium and copper acetates. For bacteriochlorins, 6-O-palmitoyl-L-ascorbic acid was additionally used as a reducing agent. MALDI mass spectrometry, which was carried out on a time-of-flight mass spectrometer Bruker Ultraflex TPF/TOF and a Bruker Daltonics Autoflex II confirmed the structure of the compounds obtained Electronic absorption spectra were obtained on a Shimadzu 3101 spectrophotometer. Fluorescence and phosphorescence spectra were obtained on a FluoTime 300 PicoQuant spectrofluorometer.Results. Photophysical studies of metal complexes showed that the introduction of palladium cations quenches fluorescence and increases the quantum yield of singlet oxygen generation to 0.98 for the chlorin conjugate. Besides, it decreases the quantum yield of fluorescence to 0.10 and increases the quantum yield of singlet oxygen generation to 0.72 for the bacteriochlorin conjugate. Introducing a copper cation to cyclen conjugates with pheophorbide and bacteriopheophorbide leads to photophysical characteristics quenching.Conclusions. Due to the stability of the synthesized metal complexes in acidic media, as well as the short metalation time (5, 20, 10, and 15 minutes) it is reasonable to expect the successful development of effective imaging agents for positron emission tomography and radionuclide therapy. In addition, the residual fluorescence of bacteriochlorins makes it possible to use fluorescence diagnostics in combination with these methods.

Wormlike micelles, which are linear aggregates created by the self-assembly of surfactants, may entangle to form dynamic three-dimensional network-like structures, endowing solutions with considerable macroscopic viscoelasticity. Recently, a pressing need has arisen to research a novel stimuli-responsive worm-like micelle that is efficient and environmentally friendly. CO2 is an inexpensive, abundant, non-toxic, biocompatible, and non-combustible gas, and it is anticipated that CO2 may serve as the trigger for stimuli-responsive worm-like micelles. In this paper, the formation of CO2-switchable pseudo-tetrameric surfactants, which subsequently self-assemble into CO2-switched wormlike micelles, is accomplished using a simple mixing of two commercial reagents, such as stearic acids and cyclen. The rheological characteristics switched by the use of CO2 are cycled between that of a low-viscosity (1.2 mPa·s) fluid and a viscoelastic fluid (worm-like micelles, 3000 mPa·s). This article expands the field of study on stimuli-responsive worm-like micelles.

Abstract Introduction An efficient and cost-effective synthesis of the metal chelating agents that couple to tumor-targeting peptides is required to enhance the process of preclinical research toward the clinical translation of molecular imaging agents. DOTA is one of the most widely used macrocyclic ligands for the development of new metal-based imaging and therapeutic agents owing to its ability to form stable and inert complexes under physiological conditions. Although solid-phase synthesis compatible DOTA-tris-(t-Bu ester) is a commercial product, it is expensive and contain chemical impurities. There is a need to explore new and cost-effective methods for the preparation of metal chelating agents, i.e., DOTA, directly on solid support to facilitate rapid, cost-effective, and high purity preparation of DOTA-linked peptides for imaging and therapy. In the present study, we describe a facile synthetic strategy of DOTA preparation and its linkage to peptides directly on solid-phase support. Methods Bombesin (BN) peptides were functionalized with DOTA chelator prepared from cyclen precursor on solid-phase and from commercial DOTA-tris and radiolabeled with 68Ga. In vitro BN/GRP receptor binding affinities of the corresponding radiolabeled peptides were determined by saturation binding assays on human breast MDA-MB-231, MCF7, T47D, and PC3 prostate cancer cells. Pharmacokinetics were studied in Balb/c mice and in vivo tumor targeting in MDA-MB-231 tumor-bearing nude mice. Results DOTA was prepared successfully from cyclen on solid-phase support, linked specifically to BN peptides and resultant DOTA-coupled peptides were radiolabeled efficiently with 68Ga. The binding affinities of all the six BN peptides were comparable and in the low nanomolar range. All 68Ga-labeled peptides showed high metabolic stability in plasma. These radiopeptides exhibited rapid pharmacokinetics in Balb/c mice with excretion mainly through the urinary system. In nude mice, MDA-MB-231 tumor uptake profiles were slightly different; the BN peptide with Ahx spacer and linked to DOTA through cyclen exhibited higher tumor uptake (2.32% ID/g at 1 h post-injection) than other radiolabeled BN peptides investigated in this study. The same leading BN peptide also displayed favorable pharmacokinetic profile in Balb/c mice. The PET images clearly visualized the MDA-MB-231 tumor. Conclusions DOTA prepared from cyclen on solid-phase support showed comparable potency and efficiency to DOTA-tris in both in vitro and in vivo evaluation. The synthetic methodology described here allows versatile, site-specific introduction of DOTA into peptides to facilitate the development of DOTA-linked molecular imaging and therapy agents for clinical translation.

The cationic ZnII part of aqua(1,4,7,10-tetraazacyclododecane)zinc(II) bis(perchlorate), [Zn(C8H20N4)(H2O)](ClO4)2, exhibits a slightly distorted square-pyramidal coordination environment with a water molecule in the apical position. In the crystal, the macrocyclic ring alternates between two conformations with equal occupancies. Two of the three perchlorate anions are situated about a twofold rotation axis, and one of them shows disorder of the O atoms with occupancies of 0.62 (7) and 0.38 (7). In the crystal, the complexes are connected by intermolecular hydrogen bonding via the perchlorate anions.

Background: Lead-212 (212Pb, t1/2 = 10.6 h) and lead-203 (203Pb, t1/2 = 51.9 h) are an element-equivalent, or a matched theranostic radioisotope pair that show great potential for application in targeted radionuclide therapy (TRT) and single-photon emission computed tomography (SPECT), respectively. At TRIUMF we have produced both 203Pb and 212Pb using TRIUMF's TR13 (13 MeV) and 500 MeV cyclotrons, and subsequently purified and evaluated both radioisotopes using a series of pyridine-modified DOTA analogues in comparison to the commercially available chelates DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) and TCMC (1,4,7,10-tetraaza-1,4,7,10-tetra(2-carbamoylmethyl)cyclododecane). Results: Proton irradiation (12.8 MeV) of natural and enriched thallium-203 (203Tl) targets gave 203Pb saturation yields of 134 ± 25 and 483 ± 3 MBq/μA, respectively. Thorium-228 (228Th, t1/2 = 1.9 y), a by-product of 232Th proton spallation on TRIUMF's main 500 MeV beamline (beamline 1A, BL1A), was recovered to build a 228Th/212Pb generator with the ability to deliver up to 9–10 MBq of 212Pb daily. Both lead isotopes were purified via solid phase extraction chromatography (Pb resin), and isolated in an acetate form ([203/212Pb]Pb(OAc)2) suitable for direct radiolabeling of chelators and bioconjugates. A series of cyclen-based chelators (herein referred to as DOTA-1Py, -2Py, and -3Py) along with established chelates DOTA and TCMC were evaluated for their ability to complex both 203Pb and 212Pb. All chelates incorporated 212Pb/203Pb efficiently, with higher radiolabeling yields observed for the 212Pb-complexes. Conclusion: The production of 203Pb and 212Pb was established using TRIUMF 13 MeV and 500 MeV cyclotrons, respectively. Both production methods provided radiometals suitable for subsequent radiolabeling reactions using known and novel chelates. Furthermore, the novel chelate DOTA-3Py may be a good candidate for biomolecule conjugation and further theranostic 212Pb/203Pb studies. [ABSTRACT FROM AUTHOR]

Tetra‐armed cyclen (1) bearing two 4‐(4′‐pyridyl)benzyl and two 3,5‐difluorobenzyl groups and its Ag+ complexes were prepared and structurally characterized. The complexes formed between 1 and Ag+ undergoes a reversible structural transformation between a 2:2 dimeric complex and a 3:5 pentacyclic trefoil complex with changes in the Ag+/1 molar ratio. It was also revealed that the 3:5 trefoil complex could encapsulate benzene and [D6]benzene selectively in solid‐state. The benzene‐included structures are stabilized by C−H⋅⋅⋅F−C interactions between the benzene molecule and the ligand molecule. [ABSTRACT FROM AUTHOR]

Oligonucleotides with the sequences 5′-GTG AUPA TGC, 5′-GCA TAUP CAC and 5′-GUPG ATA UPGC, where UP is 2′-O-propargyl uridine, were subjected to post-synthetic Cu(I)-catalyzed azide–alkyne cycloaddition to attach 1,4,7,10-tetraazacyclododecane (cyclen) and two well-known DNA intercalating dyes: thioxanthone and 1,8-naphthalimide. We propose a convenient cyclen protection–deprotection strategy that allows efficient separation of the resulting polyamine–oligonucleotide conjugates from the starting materials by RP-HPLC to obtain high-purity products. In this paper, we present hitherto unknown macrocyclic polyamine–oligonucleotide conjugates and their hybridization properties reflected in the thermal stability of thirty-two DNA duplexes containing combinations of labeled strands, their unmodified complementary strands, and strands with single base pair mismatches. Circular dichroism measurements showed that the B-conformation is retained for all dsDNAs consisting of unmodified and modified oligonucleotides. An additive and destabilizing effect of cyclen moieties attached to dsDNAs was observed. Tm measurements indicate that placing the hydrophobic dye opposite to the cyclen moiety can reduce its destabilizing effect and increase the thermal stability of the duplex. Interestingly, the cyclen-modified U showed significant selectivity for TT mismatch, which resulted in stabilization of the duplex. We conclude the paper with a brief review and discussion in which we compare our results with several examples of oligonucleotides labeled with polyamines at internal strand positions known in the literature.

Fluoride, chloride, and bromide affinities of 1,3,5‐triazacyclohexane (TACH) and 1,4,7,10‐tetraazacyclododecane (Cyclen) were studied theoretically using ωB97XD and B3LYP functionals and 6‐311++G(d,p) basis set. To enhance and modify the anion affinities of TACH and Cyclen, several anion receptors with –(CH2)nOH and –(CH2)nNH2 (n = 1–3) substituents were designed and investigated. These anion receptors are attached to the halides (X−) via formation of NH ... X and OH ... X hydrogen bonds. The anion affinities calculated by ωB97XD were larger than those obtained by B3LYP indicating the dispersion contribution to the anion affinities. It was found that the anion affinities of these compounds depend on both the alkyl chain length and nature of the interaction, NH ... X or OH ... X. The ωB97XD‐calculated fluoride affinities of TACH and Cyclen were 149.5 and 207.2 kJ mol−1, respectively. By substitution of –(CH2)nOH groups, anion receptors with F− affinities of 277 and 326 kJ mol−1 were obtained, which can be classified among the strongest organic anion receptors. The affinity of all TACH and Cyclen toward the halides was as F− > Cl− > Br−, while substitution of –(CH2)3OH and –(CH2)3NH2 into Cyclen changed the trend to F− > Br− > Cl−. [ABSTRACT FROM AUTHOR]

A new Ni(II) complex was prepared and used as a luminescent molecular thermometer. Fluorescence intensity and 13C NMR chemical shift results showed excellent linear correlations with temperature from 10 to 60 °C in acetonitrile solutions. [Display omitted] A new luminescent molecular thermometer (LMT) was prepared, characterized, and investigated. The sensor works based on the temperature effect on the spin-crossover equilibrium between two spin states of a nickel-cyclen derivative (cyclen = 1,4,7,10-tetraazacyclododecane) containing a naphthalene fragment as the emitting unit. DFT and TD– DFT calculations revealed that photoelectron transfer (PET) can partially quenches the fluorescence of the naphthalene fragment to varying degrees in both high- and low-spin states of the sensor. UV–visible spectra in coordinating solvents such as acetonitrile revealed that 80% of the predominant species adopt five-coordination in the triplet state ([Ni(cycna)(CH 3 CN)]2+) at 20 °C, while 20 % of the molecules are square planar in the singlet spin state. The fluorescence spectra showed excellent correlation of luminescence intensity with temperature (R2 = 1.00) from 10 to 70 °C, proving that the coordination compound can function as LMT. [ABSTRACT FROM AUTHOR]

A 1,4,7,10-tetraazacyclododecane (cyclen) variant bearing two thiosemicarbazone pendant groups has been prepared. The ligand forms complexes with Mn2+, Co2+ and Zn2+. X-ray crystallography of the Mn2+, Co2+ and Zn2+ complexes showed that the ligand provides a six-coordinate environment for the metal ions. The Mn2+ and Zn2+ complexes exist in the solid state as racemic mixtures of the Δ(δ,δ,δ,δ)/Λ(λ,λ,λ,λ) and Δ(λ,λ,λ,λ)/Λ(δ,δ,δ,δ) diastereomers, and the Co2+ complex exists as the Δ(δ,δ,δ,δ)/Λ(λ,λ,λ,λ) and Δ(λ,λ,λ,δ)/Λ(δ,δ,δ,λ) diastereomers. Density functional theory calculations indicated that the relative energies of the diastereomers are within 10 kJ mol−1. Magnetic susceptibility of the complexes indicated that both the Mn2+ and Co2+ ions are high spin. The ligand was radiolabelled with gallium-68, in the interest of developing new positron emission tomography imaging agents, which produced a single species in high radiochemical purity (>95%) at 90 °C for 10 min.

The crystal structure of the title salt, [Cu(ClO4)(C8H20N4)]ClO4, is reported. The CuII ion exhibits a square-pyramidal geometry and is coordinated by the four N atoms of the neutral 1,4,7,10-tetraazacyclododecane (cyclen) ligand and an O atom from one perchlorate anion, with the second perchlorate ion hydrogen-bonded to one of the amine N atoms of the cyclen ligand. Additional N—H...O hydrogen bonds between the amine H atoms and the coordinating and non-coordinating perchlorate groups create a three-dimensional network structure. Crystals were grown from a concentrated methanol solution at ambient temperature, resulting in no co-crystallization of solvent.

The supramolecular networks derived from the complexation of polyazamacrocycles with halide anions constitute fundamental building blocks of a broad range of modern materials. This study provides insights into the conformational framework that supports the binding of protonated cyclen macrocyles (1,4,7,10-Tetraazacyclododecane) by chloride anions through NHδ+···Cl− interactions. The isolated complex comprised of two cyclen hosts linked by one Cl− anion is characterized by means of infrared action spectroscopy and ion mobility mass spectrometry, in combination with quantum chemical computations. The Cl− anion is found to act as a hinge that bridges the protonated NH2+ moieties of the two macrocycles leading to a molecular tweezer configuration. Different types of conformations emerge, depending on whether the trimer adopts an open arrangement, with significant freedom for internal rotation of the cyclen moieties, or it locks in a folded conformation with intermolecular H-bonds between the two cyclen backbones. The ion mobility collision cross section supports that folded configurations of the complex are dominant under isolated conditions in the gas phase. The IRMPD spectroscopy experiments suggest that two qualitatively different families of folded conformations coexist at room temperature, featuring either peripheral or inner positions of the anion with respect to the macrocycle cavities, These findings should have implications in the growth of extended networks in the nanoscale and in sensing applications.

Featuring the dendrimer‐like properties, the cross‐linked small‐molecule micelles (cSMs) have been shown to be a good alternative to dendrimers in many applications. Following this trend, herein the copper(I)‐chelated cross‐linked cyclen micelles (CuI@cCMs) were created as a nanocatalyst for azide‐alkyne cycloaddition. Both alkynes and azides with diverse structures performed with excellent reactivity in water at the parts‐per‐million (ppm) catalyst usage. Recycle experiments disclosed that the nanocatalyst had only slight decrease of catalytic efficiency after reusing many times. Importantly, the CuI@cCMs could easily enter cells and carry out the intracellular catalysis for lighting up and/or killing cancer cells. [ABSTRACT FROM AUTHOR]

Copyright of Mugla Journal of Science & Technology is the property of Mugla Journal of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Graphical abstract Several bis-aryl-monocyclic polyamines and their metal complexes were shown to be potent in vitro inhibitors of Leishmania donovani. The synthesis of the two most promising compounds, Fe L7 Cl 2 and Mn L7 Cl 2 , are shown below. Abstract A total of 44 bis-aryl-monocyclic polyamines, monoaryl-monocyclic polyamines and their transition metal complexes were prepared, chemically characterized, and screened in vitro against the Leishmania donovani promastigotes, axenic amastigotes and intracellular amastigotes in THP1 cells. The IC 50 and/or IC 90 values showed that 10 compounds were similarly active at about 2-fold less potent than known drug pentamidine against promastigotes. The most potent compound had an IC 50 of 2.82 µM (compared to 2.93 µM for pentamidine). Nine compounds were 1.1–13.6-fold more potent than pentamidine against axenic amastigotes, the most potent one being about 2-fold less potent than amphotericin B. Fourteen compounds were about 2–10 fold more potent than pentamidine, the most potent one is about 2-fold less potent than amphotericin B against intracellular amastigotes in THP1 cells. The 2 most promising compounds (Fe L7 Cl 2 and Mn L7 Cl 2), with strong activity against both promastigotes and amastigotes and no observable toxicity against the THP1 cells are the Fe2+- and Mn2+-complexes of a dibenzyl cyclen derivative. Only 2 of the 44 compounds showed observable cytotoxicity against THP1 cells. Tetraazamacrocyclic monocyclic polyamines represent a new class of antileishmanial lead structures that warrant follow up studies. [ABSTRACT FROM AUTHOR]

The development of lanthanide-based luminescent probes with a long emission lifetime has the potential to revolutionize imaging-based diagnostic techniques. By a rational design strategy taking advantage of computational predictions, a novel, water-soluble Eu3+ complex from a cyclen-based ligand bearing 1,3-disubstituted benzo[h]isoquinoline arms was realized. The ligand has been obtained overcoming the lack of reactivity of position 3 of the isoquinoline moiety. Notably, steric hindrance of the heteroaromatic chromophore allowed selective and stoichiometry-controlled insertion of two or three antennas on the cyclen platform without any protection strategy. The complex bears a fourth heptanoic arm for easy conjugation to biomolecules. This new chromophore allowed the sensitization of the metal center either with one or two photons excitation. The suitability as a luminescent bioprobe was validated by imaging BMI1 oncomarker in lung carcinoma cells following an established immunofluorescence approach. The use of a conventional epifluorescence microscope equipped with a linear structured illumination module disclosed a simple and inexpensive way to image confocally Ln-bioprobes by single photon excitation in the 350–400 nm window, where ordinary confocal systems have no excitation sources.

[Display omitted] The coordination properties of the macrocycle 1,4,7,10-tetrakis(2,4-dimethyl-1-hydroxy-6-methyl-benzyl)-1,4,7,10-tetraazacyclododecane, H 4 LMe,Me have been investigated with lanthanides La(III) and Pr(III) and 3/4 d metal ions Zn(II) and Y(III). Two Pr(III) complexes [Pr(HLMe,Me)]‧MeOH (2a) and [Pr(HLMe,Me)]‧2H 2 O (2b) with coordination numbers (C.N.) 7 and 8, respectively as well as the [La(HLMe,Me)]‧2H 2 O (1) complex, which was isomorphic with 2b were isolated. In addition, [Y(HLMe,Me)]‧CH 3 CN‧H 2 O (3) and [Zn(H 3 LMe,Me)](NO 3) (4) with C.N. 7 and 5, respectively were synthesized too. All complexes were spectroscopically and structurally characterized as well as luminescence emission of 2a and 2b. [ABSTRACT FROM AUTHOR]

• The effect of the amine moiety on the ferrocene oxidation mechanism was investigated. • Cyclic voltammograms and bulk electrolysis with product isolation were used to obtain the oxidation mechanism. • The effect of cyclen and cyclam on the ferrocene oxidation potential was investigated. • The ability of the complexes to work as electrochemical sensors for Cu2+, Co2+, Cd2+, Zn2+, or Ni2+ ions is discussed. The ligands [R-Fc(cyclen)], [Fc(cyclen) 2 ], [Fc(cyclam) 2 ], [Fc 2 (cyclen)] and [Fc 4 (cyclen)] (R = –H or –CH 2 OH; Fc = ferrocene; cyclen = 1,4,7,10-tetraazacyclododecane; cyclam = 1,4,8,11-tetraazacyclotetradecane) and their respective Cu2+, Co2+, Cd2+, Zn2+, and Ni2+ metal complexes have been synthesised and electrochemically characterised. The voltammetry of the free ligands in a CH 2 Cl 2 /CH 3 CN (1:4) solvent mixture containing [Bu 4 N][PF 6 ] or [Bu 4 N](B(C 6 F 5) 4 ] as the supporting electrolyte yields two closely spaced oxidation processes. The first one is Fc based, and the other is related to the interaction of the Fc with the nitrogen component. Details of the mechanism were established by studying the oxidation of N , N -dimethylaminomethylferrocene by cyclic voltammetry and bulk electrolysis with product isolation. However, cyclic voltammetries exhibit a single Fc-based reversible oxidation process when the ligands form metal complexes with Cu2+, Co2+, Cd2+, Zn2+, or Ni2+. Upon metal ion binding, an important positive shift in the reversible midpoint potential, E m , is observed. The magnitude of the shift in the E m values follows the order [Fc(cyclen) 2 ] ≈ [Fc(cyclam) 2 ] ≫ [R-Fc(cyclen)] ≈ [Fc 2 (cyclen)] > [Fc 4 (cyclen)]. The ability of the ligands to work as electrochemical sensors for the mentioned cations is discussed. [ABSTRACT FROM AUTHOR]

• Peptide-modified cyclen and L-DOPA derivatives were synthesized. • In vitro anti-inflammatory, ORAC, and AChE inhibitory activities were evaluated. • The effectiveness of compounds against Alzheimer's diseases was confirmed. 1,4,7,10-tetraazacyclododecane (cyclen), a macrocyclic polyamine, and L-3,4-dihydroxyphenylalanine (L-DOPA), a tyrosine polyphenolic compound are compounds having various applications in medicine, biology, chemistry, etc. Derivatization of these precursor compounds aims to increase their biological activity, blood-brain barrier (BBB) permeability, solubility, binding ability, and lower toxicity. Synthesis and in vitro cytotoxicity of small new peptide-modified cyclen and L-DOPA derivatives were described previously. In the present study, in vitro biological activities such as radical scavenging capacity, anti-inflammatory, and acetylcholinesterase (AChE) inhibitory activities of compounds were evaluated. The results showed that some of them are good candidates for further detailed studies targeting neurodegenerative diseases, such as Alzheimer's and Parkinson's, and their pharmacokinetics and interaction with amyloidal aggregations characterized for neurodegenerative diseases. Dopa-DH-Dopa showed the highest anti-oxidant activity (IC 50 , 0.12 µM) and Dopa-HH-Dopa as AChE inhibitor (21 µM). Dopa-HH mainly inhibited nitric oxide (NO) production as an inflammatory marker. [Display omitted] [ABSTRACT FROM AUTHOR]

An efficient protocol for the direct synthesis of N-tetraalkylated derivatives of the azamacrocycles cyclam and cyclen has been developed, using a partially miscible aqueous–organic solvent system with propargyl bromide, benzyl bromide, and related halides. The method works most effectively when the reaction mixture is shaken, not stirred. A crystal structure of the N-tetrapropargyl cyclam derivative 1,4,8,11-tetra(prop-2-yn-1-yl)-1,4,8,11-tetraazacyclotetradecane diperchlorate is reported.

Metal complexes of cyclen have been widely used to hydrolytically cleave biomolecules (proteins, RNA, DNA) and model substrates. Such cleavage reactions, however, usually require a high pH, long incubation times and enhanced temperatures. The present study combines two straightforward approaches to increase the proteolytic cleavage activity of cyclen complexes: alkylation in order to improve interactions with hydrophobic domains of proteins as well as single and double heteroatom exchange in order to increase the Lewis acidity of the metal center, in this case Cu(II). This allows reactions with BSA and Mb as model proteins to be carried out also at near‐physiological conditions. A Cu(II) complex with an alkylated oxacyclen ligand was identified as the most efficient species. Furthermore, a dioxacyclen derivative was investigated in proteolytic reactions for the first time. Cyclen complexes are known to cleave peptide bonds of proteins. In order to improve interactions with hydrophobic domains of proteins, alkyl chains were appended to cyclen ligands. Additionally, heteroatom exchange within the cyclen was exploited in order to increase the Lewis acidity of the metal center. This allowed reactions with BSA and Mb as model proteins to be carried out also at near‐physiological conditions. [ABSTRACT FROM AUTHOR]

Polyazamacrocycles and its functionalized derivatives have been employed recently as organic building blocks in the construction of extended metal–organic frameworks (MOFs). Incorporating azamacrocycles into the MOF architectures not only merges the chemistry of MOFs with supramolecular chemistry of the macrocycles, but also brings out novel properties from the hybrid frameworks produced. In this review, we describe recent advances of the fabrication of azamacrocycles into MOF structures along with the most prominent applications based upon azamacrocycle-containing MOFs, which include molecular recognition and separation, template synthesis, gas adsorption, and heterogenous catalysis. [ABSTRACT FROM AUTHOR]

Single crystals of two novel uranyl sulfates and two novel uranyl selenates with protonated cyclen and 3-aminotropane molecules, ((C8H24N4)[(UO2)3(SO4)5](H2O)3 (I), (C8H24N4)(H5O2)(H3O)[(UO2)4(SeO4)7(H2O)](H2O)6.6 (II), (C8H18N2)(H5O2)(H3O)[(UO2)3(SO4)5(H2O)](H2O)0.5 (III), and (C8H18N2)(H5O2)(H3O)[(UO2)3(SeO4)5 (H2O)](H2O)2 (IV) have been prepared by isothermal evaporation from aqueous solutions and structurally characterized. Uranyl-containing 2D units have been investigated using topological approach and information-based complexity measures demonstrating that complex topologies form more rare than their simplest counterparts, which is a response of the crystal structure to changes of chemical conditions within the system. [ABSTRACT FROM AUTHOR]

A temperature responsive carbonic anhydrase mimicking compound (PNiPAm-co-CyclenZn) was synthesised and characterized to assess its potential as a rate promoter for carbon dioxide (CO 2 ) capture using solvent absorption. Development of novel rate promoters, such as the catalytic polymer discussed in this study, can improve reaction kinetics and reduce the cost of CO 2 capture. Results showed that the lower critical solution temperature (LCST) of PNiPAm-co-CyclenZn is 33.7 °C which is close to the physiological temperature. Above the LCST, PNiPAm- co -CyclenZn undergoes a phase transition from a swollen hydrated state to a shrunken dehydrated state. This property can potentially enable easy separation of PNiPAm-co-CyclenZn from the CO 2 loaded solution exiting the absorber column so that it does not enter the high temperature stripping column. In the reaction between CO 2 and H 2 O, the catalysis coefficient at 298 K of PNiPAm-co-CyclenZn was determined to be 380 ± 20 M −1 s −1 at a pH of 7.36 and 2330 ± 40 M −1 s −1 at a pH of 9.06. Arrhenius fitting of the catalysis coefficients showed an activation energy of 60 ± 2 kJ/mol at pH of 7.36. This study presents the first example of a temperature responsive polymeric catalyst for carbon dioxide absorption. The catalyst was developed with the aim of increasing the absorption rates of carbon dioxide in bicarbonate forming amine solutions and carbonate solvents that have slow absorption kinetics. [ABSTRACT FROM AUTHOR]

Selective lithium recovery from salt lake brine using emerging nanofiltration membranes is expected to solve the insufficient supply of lithium resources. In this work, 1,4,7,10-tetraazacyclododecane (Cyclen) was employed as a novel structural regulator through interfacial polymerization of polyethyleneimine (PEI) and trimesoyl chloride (TMC) to develop polyamide NF membrane with efficient Li+/Mg2+ separation performance. After the introduction of Cyclen to aqueous phase, the PEI/Cyclen-TMC selective layer was confirmed to possess a higher crosslinking degree and larger d-spacing than PEI-TMC layer, endowing a dedicated channel for Li+ transport. The water permeance of PEI/Cyclen-TMC composite membrane reached 14.0 L·m−2·h−1·bar−1, about 3.8 times higher than PEI-TMC composite membrane, and meanwhile the separation factor (S Li,Mg) could be stabilized as 8.7 to realize a considerable reduction of Mg2+/Li+ mass ratio from 20 to 2.3. Additionally, PEI/Cyclen-TMC composite membrane was utilized to operate a three-stage nanofiltration treatment procedure of a simulated salt lake brine (Mg2+/Li+ mass ratio: 40). The results indicated that Li+ could be efficiently retracted to obtain a solution with 19.5 mg·L−1 Li+ and Mg2+/Li+ mass ratio of 0.3. After the subsequent precipitation and filtration, the obtained Li 2 CO 3 purity could reach 93 %, indicating the potential application of nanofiltration for lithium recovery. 1,4,7,10-tetraazacyclododecane (Cyclen) with cavity structure and selective coordination properties for Li+ ions was employed as a novel structural regulator to fabricate nanofiltration composite membrane for Li+/Mg2+ separation. After a three-stage nanofiltration treatment of simulated salt lake brine, Li+ was efficiently retracted from a simulated salt lake brine (Mg2+/Li+ mass ratio: 40) to a solution with 19.5 mg·L−1 Li+ and Mg2+/Li+ mass ratio of 0.3, indicating the potential application of nanofiltration process for lithium recovery. [Display omitted] • Cyclen with cavity structure and selective coordination properties for Li+ ions • PEI/Cyclen-TMC membrane showing high water permeance and separation factor (S Li,Mg) • Li+ extraction from simulated salt lake brine after a three-stage NF and precipitation [ABSTRACT FROM AUTHOR]

Toxic metal (Cd2+, Hg2+, Pb2+, and Ag+) complexes with the tetradentate macrocyclic ligand - cyclen (1,4,7,10-tetraazacyclododecane, [12]aneN4, L) were prepared and studied in the solid state by IR, X-ray diffraction, elemental and thermal analysis. Diffraction results have yielded three molecular structures, [Cd([12]ane-κ4N1,4,7,10)(NO3)2)] (1), [Hg([12]ane-κ4N1,4,7,10)(NO3-κ2O,O`)]NO3(2), [Pb2([12]ane-κ4N1,4,7,10)2][Pb(NO3)6] (3) and one polymeric structure {[Ag2([12]ane-κ3N1,4,7)(μ2-[12]aneN10)](NO3)2∙2H2O)}n(4) featuring a unique coordination mode not observed before with cyclen as a ligand. The monodentate (1) and chelate (with small bite angle 50.3(3)°, (2) coordination modes of nitrate ligands were confirmed. Stereochemically active 6s2lone pair was suggested in3and DFT results confirmed no significant metal–metal covalent bond. The stability constants of the complexes with Cd2+and Pb2+ions were determined by potentiometric methods in aqueous solutions. Additionally, the structures of complexes in solution were observed by1H NMR. Both methods confirm similar cyclen complexing properties toward Zn2+biometal and Cd2+, Pb2+toxic metals. [ABSTRACT FROM AUTHOR]

Luminescent Eu(III)- and Tb(III)-complexes based on functionalized tetraazamacrocycle (cyclen) or dipicolinic acid (dpa) metal binding sites, and carrying 2′- or 5′-linked uridine moieties were prepared. The light-harvesting antennae were either a coumarin (in the cyclen-based architectures) or the dpa-moiety itself. Antenna excitation resulted in metal-centered emission for all complexes. The presence of the uridine resulted in less intense lanthanide emission compared to non-nucleotide-modified reference compounds. Nd(III)-complexes of cyclen ligands carrying a uridine but without a sensitizing antenna were also synthesized; these are envisioned as energy transfer acceptors to the Eu(III)-complexes. The possibility for Eu-to-Nd energy transfer was probed. The reported complexes are models for oligonucleotide-attached lanthanide probes. [ABSTRACT FROM AUTHOR]

New cyclen (1,4,7,10-teraazacyclododecane) cored dendrimers up to the second generation, functionalized with 4, 8 and 16 pyrene units, respectively, were synthesized following a convergent procedure. All new compounds were characterized by NMR spectroscopies and ESI or MALDI TOF mass spectrometry. The optical and photophysical properties of the new dendrimers were studied in THF solution. Absorption spectra showed the typical absorption bands of pyrene moieties. In the fluorescence spectra, monomer as well as excimer emission were observed for all compounds. An increased proportion of excimer emission was observed in the dendrimer of the highest generation. [ABSTRACT FROM AUTHOR]

In this study firstly, phosphazene crosslinked cyclen microspheres were synthesized. Then, supported copper nanoparticles were prepared on these phosphazene crosslinked cyclen microspheres for use as a metal catalyst. The prepared microparticles and microparticle-supported metal catalyst were characterized using FT-IR, SEM-EDX, TEM and XPS analysis. Also, the prepared metal composite was used as a catalyst for the reduction reaction of 4-nitrophenol in the presence of NaBH in aqueous media. The catalytic activity of the Cu-cyclen composite catalyst was investigated using UV-Vis spectroscopy. The reduction studies were completed at four different temperatures (30-60 °C). The activation parameters were calculated from the obtained rate constants at the four different temperatures (30-60 °C). The activation energy, activation enthalpy and activation entropy for the reduction reaction of 4-NP in the presence of Cu-cyclen composite catalyst were calculated as 39.88, 36.56 and −143.30 kJmol, respectively. The total turnover frequency (TOF) for Cu-cyclen composite catalyst was 0.794 mol 4-NP (mol Cu) (min). [ABSTRACT FROM AUTHOR]

The crystal structure of the title salt, [Cu(ClO4)(C8H20N4)]ClO4, is reported. The CuII ion exhibits a square-pyramidal geometry and is coordinated by the four N atoms of the neutral 1,4,7,10-tetraazacyclododecane (cyclen) ligand and an O atom from one perchlorate anion, with the second perchlorate ion hydrogenbonded to one of the amine N atoms of the cyclen ligand. Additional N-H…O hydrogen bonds between the amine H atoms and the coordinating and noncoordinating perchlorate groups create a three-dimensional network structure. Crystals were grown from a concentrated methanol solution at ambient temperature, resulting in no co-crystallization of solvent. [ABSTRACT FROM AUTHOR]

[Display omitted] • A cyclen-linked benzoquinone based carbonyl network polymer (NP4) is synthesized. • NP4-based cathode exhibits a specific capacity of 260.7 mA h g−1. • NP4 allows excellent stability of 80% capacity retention after 4000 cycles. Carbonyl polymers for cathodes of lithium batteries have attracted wide attention owing to their diverse and finely tuned structures. However, the problem of poor cycling performance caused by the dissolution of the carbonyl polymer electrodes in the electrolyte hinders their further development. Here, we design and report a cyclen-linked benzoquinone based carbonyl network polymer (NP4), which when used as the cathode material in lithium organic batteries, exhibits a specific capacity of 260.7 mA h g−1 at a current density of 20 mA g−1. Compared to the previously reported carbonyl linear polymer NP2, the stable network chemical structure of NP4 allows excellent capacity retention (80 % after 4000 cycles at 500 mA g−1). These results demonstrate that polymer NP4 with a network chemical structure exhibits excellent battery performance as a lithium battery cathode. This work shows that NP4 is a good cathode material for lithium batteries and opens a wide range of prospects for energy storage in carbonyl network polymers. [ABSTRACT FROM AUTHOR]

The discharge of wastewater containing organic micropollutants not only causes severe environmental pollution, but also exacerbates the scarcity of freshwater resources and poses a serious threat to human health. The nanofiltration (NF) membrane has unique advantages and obvious energy-saving effects in the demineralization of organic micropollutants. Poly(piperazine) amide NF membrane exhibits the poor organic micropollutants/salt selectivity and low water permeance. Therefore, developing a novel NF membrane with high water permeance and superior selectivity is of significance. In this study, a loose nanofiltration (LNF) membrane is fabricated by interfacial polymerization with 1, 4, 7, 10-tetraazacyclododecane (Cyclen) as a new aqueous phase monomer to modulate the polyamide microstructure. The steric structure of Cyclen is larger than that of PIP, and the steric hindrance increases, resulting in a low stacking density of the formed polyamide polymer. Compared with the PIP-based NF membrane, the fabricated Cyclen-TMC LNF membrane has a smoother surface, a higher density of carboxyl groups, and a lower degree of cross-linking. The Cyclen-TMC membrane exhibits the considerable water permeance, with the corresponding rejection of 99.9% and 92.7% for methyl blue and tetracycline (pH = 9), respectively, while maintaining a low rejection for monovalent salts (e.g., 4.5% for NaCl). Furthermore, the LNF membrane shows a superior anti-fouling performance with the relatively smooth, highly negatively charged surface and low operation pressure. The novel LNF membrane exhibits a high potential for textile and pharmaceutical wastewater treatment. This study provides a new candidate to regulate the separation performance of NF membranes using new aqueous monomers. [Display omitted] • A novel aqueous phase monomer is designed for the fabrication of loose nanofiltration membrane. • The separation layer is relative smooth, highly negative-charged and loose. • The membrane has a desirable separation performance and a superior antifouling performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • High SOD activity of Cu(II) complexes upon covalent immobilization in aerogel. • EPR and SANS show the molecular level separation of the complexes in the aerogel. • EPR data show the formation of new coordination modes in the aerogel. • Chemical environment, coordination mode, separation alter reactivity of complexes. • SOD mimetic aerogels form stable microparticles in water. The copper(II) complexes of 1,4,7,10-tetraazacyclododecane (cyclen) and 1,4,8,11- tetraazacyclotetradecane (cyclam) were covalently immobilized in mesoporous silica aerogels by the sol–gel method using functionalized silica precursors. The modified macrocyclic precursors are characterized by mass spectrometry (MS) and solution phase nuclear magnetic resonance (NMR) spectroscopy. The supercritically dried aerogels are characterized using low voltage scanning electron microscopy (LV-SEM), N 2 -sorption porosimetry, infrared spectroscopy (FT-IR), electron paramagnetic resonance spectroscopy (EPR) and contrast variation small angle neutron scattering (SANS). The suspended aerogel particles act as nanoenzymes, because they have significant SOD activities, dramatically higher than the corresponding dissolved Cu(II) complexes. The most important factors responsible for the altered reactivities due to the covalent immobilization of the complexes were elucidated based on the compiled results of the characterization methods. These are: i) the formation of new chemical environments and Cu(II) coordination modes; ii) the effective separation of the active Cu(II) centers in the aerogels; and iii) the confinement effect operative in the nanoporous network. As a perspective, the present functionalized aerogel microparticles can be developed into passive targeting antioxidant pharmaceutical agents administered locally or subcutaneously. [ABSTRACT FROM AUTHOR]

[Display omitted] • FU–-bound Zn(II)–cyclen complex was characterized in the crystalline/solution states. • X-ray crystallography revealed the complex structure of 1:1 FU–-bound ZnL2+. • The pH titration showed that log K value was almost the same as that of ftorafur. Structural and biological properties of 5-fluorouracil (FU) bound zinc(II)–cyclen complex (FU––ZnL2+, L = cyclen; 1,4,7,10-tetrazacyclododecane) were studied in to develop an anticancer drug candidate. The complex formation was analyzed by X-ray crystallography and pH-titration study, and the anticancer activity was investigated by cytotoxicity examination against HL-60 cells. The crystal structure revealed that FU– and ZnL+ form the complex with 1:1 stoichiometry. The pH titration study proved that FU– has a strong affinity to ZnL+ at the physiological pH range (6.5–9.0). The IC 50 values of FU––ZnL2+ against HL-60 cells growth was 132 μM in a quantitating cellular ATP levels. These results provide the basis for designing novel anticancer drug complexes and controlling FU release. [ABSTRACT FROM AUTHOR]

For nanofiltration membranes, the selective separation of divalent/monovalent cations with high permeance is a desirable yet challenging demand due to the trade-off phenomenon between the perm-selectivity and permeance. In this study, a novel macrocyclic polyamine 1, 4, 7, 10-tetraazacyclododecane (Cyclen) is used as the aqueous phase monomer to construct a nanofiltration (NF) membrane with high permeance without sacrificing the perm-selectivity. The large molecular size of Cyclen greatly limits its interfacial mass transfer across the water/oil interface, resulting in the formation of many defects in the separation layer. Based on the widely applied interlayer technology in literature, a surfactant-assembly regulated interfacial polymerization (SARIP) is adopted to intensify the phase transfer process of the Cyclen. The interlayer accommodates enough Cyclen monomers and the surfactant acts as the phase transfer catalyst, which jointly enhance the monomer's phase transfer rate. The resultant polyamide membrane yields a uniform sub-nanometre pore size, and the combination of reduced pore size and charge distribution within the pores achieves high rejection for divalent ions and low rejection of monovalent ions, with the rejection order of LiCl (18.9 %) < NaCl (24.8 %) < MgSO 4 (96.2 %) < MgCl 2 (96.3 %) < Na 2 SO 4 (97.0 %). The corresponding water permeance for MgCl 2 reaches up to 18.5 L·m−2·h−1·bar−1 with the desirable Li+/Mg2+ and Na+/Mg2+ perm-selectivity of 21.9 and 20.3, respectively. [Display omitted] • Cyclen is used to construct a NF membrane with high permeability and considerable perm-selectivity. • An interlayer and surfactant are adopted to intensify the phase transfer process of Cyclen. • The resultant polyamide membrane yields a uniform sub-nanometre pore size. • The membrane exhibits a desirable cation perm-selectivity. [ABSTRACT FROM AUTHOR]

Magnetic Resonance Imaging (MRI) is a noninvasive radiology technique used to examine the internal organs of human body. It is useful for the diagnosis of structural abnormalities in the body. Contrast agents are used to increase the sensitivity of this technique. 1,4,7,10-Tetraazacyclododecane (cyclen) is a macrocyclic tetraamine. Its derivatives act as useful ligands to produce stable complexes with Gd 3+ ion. Such chelates are investigated as MRI contrast agents. Free Gd 3+ ion is extremely toxic for in vivo use. Upon complexation with a cyclen-based ligand, it is trapped in the preformed central cavity of the ligand resulting in the formation of a highly stable Gd 3+ -chelate. Better kinetic and thermodynamic stability of cyclen-based MRI contrast agents decrease their potential toxicity for in vivo use. Consequently, such agents have proved to be safest for clinical applications. Relaxivity is the most important parameter used to measure the effectiveness of a contrast agent. A number of factors influence this parameter. This article elucidates detailed strategies to increase relaxivity of cyclen-based MRI contrast agents. 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) and 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3A) are two key ligands derived from cyclen. They also act as building blocks for the synthesis of novel ligands. A few important methodologies for the synthesis of DOTA and DO3A derivatives are described. Moreover, the coordination geometry of chelates formed by these ligands and their derivatives is discussed as well. Novel ligands can be developed by the appropriate derivatization of DOTA and DO3A. Gd 3+ -chelates of such ligands prove to be useful MRI contrast agents of enhanced relaxivity, greater stability, better clearance, lesser toxicity and higher water solubility. [ABSTRACT FROM AUTHOR]

Several paramagnetic chemical exchange saturation transfer magnetic resonance imaging (PARACEST MRI) agents for the potential detection of nitric oxide synthase (NOS) have been synthesized and evaluated. These agents are based on an amino acid- or dipeptide-decorated DOTAM (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid amide) chelator possessing either Tm3+ or Dy3+. The amino acid and dipeptide decorated DOTAMs were designed such that the terminal amino acid pendant group was l-arginine, which may be converted to l-citrulline by NOS. Preliminary evaluation has revealed that some of the l-arginine-decorated complexes are recognized and metabolized by the NOS. Differences in the CEST properties between Dy3+-metallated l-arginine- and l-citrulline-modified complexes suggest that these might be suitable for imaging of the NOS enzymatic activity. [ABSTRACT FROM AUTHOR]

Hybrid complexes with N,N′-bis(2-benzimidazolylmethyl)amine and cyclen moieties are novel enzyme mimics and controlled DNA release materials, which could interact with DNA through three models under different conditions. In this paper, the interactions between plasmid DNA and seven different complexes were investigated, and the methods to change the interaction patterns by graphene oxide (GO) or concentrations were also investigated. The cleavage of pUC19 DNA promoted by target complexes were via hydrolytic or oxidative mechanisms at low concentrations ranging from 3.13 × 10-7 to 6.25 × 10-5 mol/L. Dinuclear complexes 2a and 2b can promote the cleavage of plasmid pUC19 DNA to a linear form at pH values below 7.0. Furthermore, binuclear hybrid complexes could condense DNA as nanoparticles above 3.13 × 10-5 mol/L and partly release DNA by graphene oxide with π - π stacking. Meanwhile, the results also reflected that graphene oxide could prevent DNA from breaking down. Cell viability assays showed dinuclear complexes were safe to normal human hepatic cells at relative high concentrations. The present work might help to develop novel strategies for the design and synthesis of DNA controllable releasing agents, which may be applied to gene delivery and also to exploit the new application for GO. [ABSTRACT FROM AUTHOR]