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PubMed2005

Electron paramagnetic resonance study of partially oriented clay platelets intercalated with copper(II) 1,4,8,11-tetraazacyclotetradecane.

Electron paramagnetic resonance (EPR) spectra of powder and oriented films of montmorillonite, hectorite, and saponite intercalated with [Cu(cyclam)](2+) (cyclam = 1,4,8,11-tetraazacyclotetradecane) exhibit three components: an orientation-dependent component without hyperfine features, an orientation-dependent component with hyperfine features, and an orientation-independent component without hyperfine feature. EPR spectra of [Cu(cyclam)](2+)-saponite, which exhibit only two components and the best resolved hyperfine features, were simulated. The spectra indicate that a large portion of the saponite platelets are inclined to the glass surface, although they tend to align with their basal planes parallel to the glass surface. The orientation-dependent spectra could be simulated by introducing a Gaussian distribution with a standard deviation of 20 degrees for the inclination angle. The standard deviation may be used as a disorder parameter for the microcrystals assembled on glass plates. Spectral simulation also shows that the CuN(4) plane of [Cu(cyclam)](2+) is parallel to the clay layers. EPR spectra of some other partially oriented systems are also discussed.

Aluminum Silicates↗
PubMed2001

Mu-peroxo-bis[trans-chloro(1,4,8,11-tetraazacyclotetradecane)cobalt(III)] bis(tetraphenylborate) diacetone solvate.

The title complex, [Co(2)Cl(2)(mu-O(2))(cyclam)(2)](C(24)H(20)B)(2).2Me(2)CO, was obtained when [Co(cyclam)Cl(2)](BPh(4))(2) was crystallized from acetone in air; cyclam is 1,4,8,11-tetraazacyclotetradecane, C(10)H(24)N(4). The peroxo O-O moiety straddles a crystallographic centre of inversion (the two octahedral Co atoms are symmetrically bridged by the O(2) moiety), hence only half of the complex cation is in the asymmetric unit. A comparison of the O-O [1.483 (3) A], Co-Cl [2.2647 (8) A] and Co-O [1.894 (2) A] bond lengths with similar bonds in previously determined structures indicates the oxidation of Co(II) to Co(III) during the crystallization process. In the crystal lattice, cation dimers are encapsulated by six [BPh(4)](-) anions, with C-H...pi hydrogen bonds between the cyclam methylene groups and the phenyl rings of the anion.

Journal Article↗
PubMed1992

Synthesis and renal excretion of technetium-99m-labeled organic cations.

Organic cations are excreted more efficiently than organic anions in uremia suggesting superiority as renal imaging agents. In this study, three 99mTc-labeled cationic cyclam complexes were synthesized and their renal clearance quantified in rats. The complexes are cleared at a rate of about 2.5-3 times that of inulin and about 60% that of p-amino-hipurate. Inhibition of 99Tc-cyclam excretion by quinine indicates transport by the organic cation process. Comparative in vivo imaging experiments demonstrated that in normal rats 99mTc-cyclam reached peak renal activity 1.8 +/- 0.6 min after injection, a value intermediate between that for [131I]OIH (1.0 +/- 0) and 99mTc-MAG3 (2.8 +/- 0.6). In rats injected with the acute nephrotoxin cisplatin, the times to peak were lengthened with the relative order being 99mTc-cyclam > 99mTc-MAG3 > [131I]OIH. The results demonstrate that cationic complexes may be useful for renal imaging diagnostic applications.

Animals↗
PubMed1987

Anion dependence of Ca2+ transport and (Ca2+ + K+)-stimulated Mg2+-dependent transport ATPase in rat pancreatic endoplasmic reticulum.

Anion dependence of (Ca2+ + K+)-stimulated Mg2+-dependent transport ATPase and its phosphorylated intermediate have been characterized in both "intact" and "broken" vesicles from endoplasmic reticulum of rat pancreatic acinar cells using adenosine 5'-[gamma-32P] triphosphate ([gamma-32P]ATP). In intact vesicles (Ca2+ + K+)-Mg2+-ATPase activity was higher in the presence of Cl- or Br- as compared to NO3-, SCN-, cyclamate-, SO4(2-) or SO3(2-). Incorporation of 32P from [gamma-32P]ATP into the 100-kDa intermediate of this Ca2+ATPase was also higher in the presence of Cl-, Br-, NO3- or SCN- as compared to cyclamate-, SO4(2-) or SO3(2-). When the membrane permeability barrier to anions was abolished by breaking vesicle membrane with the detergent Triton X-100 (0.015%) (Ca2+ + K+)-Mg2+ATPase activity in the presence of weakly permeant anions, such as SO4(2-) and cyclamate-, increased to the level obtained with Cl-. However, 32P incorporation into 100-kDa protein was still higher in the presence of Cl- as compared to cyclamate-, indicating a direct effect of Cl- on the Ca2+ATPase molecule. The anion transport blocker 4,4-diisothiocyanostilbene-2,2-disulfonate (DIDS) inhibited (Ca2+ + K+)-Mg2+ATPase activity to about 10% of the Cl- stimulation level, irrespective of the sort of anions present in both intact and broken vesicles. This indicates a direct effect of DIDS on (Ca2+ + K+)-Mg2+ATPase. K+ ionophore valinomycin influenced (Ca2+ + K+)-Mg2+ATPase activity according to the actual K+ gradient: Ko+ greater than Ki+ caused inhibition, Ko+ less than Ki+ caused stimulation. From these results we conclude that Ca2+ transport into endoplasmic reticulum is coupled to ion movements which must occur to maintain electroneutrality.

Animals↗
PubMed1982

In vivo and in vitro studies with sulfamate sweeteners.

The sweet compounds 2-methyl- and 3-methylcyclohexyl- and 2-cyclohexenylsulfamates were fed to Wistar albino rats. The urine (and feces in the case of 2-cyclohexenylsulfamate) was examined for possible amine, ketone, and alcohol metabolites. The total percent of metabolites formed was low and the hexenyl compound gave a particularly small quantity of metabolite. The results with these compounds are compared with those obtained from earlier in vivo studies with cyclamate and other sulfamates. In complementary in vitro studies, the four sweetest sulfamates, namely, cyclamate, cycloheptyl-, cyclooctyl-, and cyclopentylsulfamates were incubated with the cell-free extract of bacteria isolated from the feces of cyclamate fed rats. Some correlation was apparent between these in vitro experiments and previous in vivo studies. Preliminary mutagenicity testing (the Ames test) of some amines (corresponding to the sulfamates studied) has been carried out.

Animals↗
PubMed1985

Moderate intake of sucrose does not impair metabolic control in pump-treated diabetic out-patients.

The effects of dietary intake of sucrose versus the use of sodium cyclamate were studied in 10 Type 1 (insulin-dependent) diabetic patients on continuous subcutaneous insulin infusion therapy. After a 4-week run-in period, the patients were randomly assigned to a cross-over protocol with two 4-week periods during which they used sucrose or sodium-cyclamate as sweetener. During the experimental periods, 24 +/- 13 g/day sucrose and 348 +/- 270 mg/day of sodium cyclamate were consumed, respectively. Metabolic control was monitored by the patients performing blood glucose self-monitoring several times daily. Bi-weekly, all patients were followed-up in our outpatient clinic. Mean daily blood glucose concentrations as well as the average daily insulin dose did not differ between the three experimental periods. HbA1c-levels, serum lipids and body weight remained unchanged and within the normal ranges throughout the study. Thus, moderate dietary intake of sucrose did not affect metabolic control in these normal weight, near-normoglycaemic, normolipidaemic, pump-treated Type 1 diabetic patients during a 1-month period. Whether similar conclusions apply to less well controlled diabetic patients remains to be seen.

Adult↗
PubMed1988

Uptake of saccharin and related intense sweeteners by Streptococcus mutans NCTC 10449.

In a 1-octanol/phosphate buffer system, saccharin was much more lipophilic than would be inferred from its dissociation constant which, however, determined the partition behavior of acesulfame and cyclamate. The uptake of saccharin into Streptococcus mutans led to a 30 to 40-fold higher concentration of this intense sweetener within cells than in the incubation medium. Acesulfame and cyclamate were distributed between cells and medium essentially in a diffusion-controlled manner. The uptake of saccharin into S. mutans was found to depend strongly on simultaneous sugar fermentation, and in addition, on external pH, sweetener concentrations, and cell densities. Without glycolysis, caused, for example, by an exhaustion of added sucrose, too acidic external pH, or the addition of glycolysis inhibitors, the uptake of saccharin was diffusion-controlled as in the case of acesulfame and cyclamate. The uptake of saccharin was inhibited by a reversal of the direction of the lactate gradient from in----out to out----in. The activation energy of saccharin uptake into glycolyzing S. mutans was near 18 kJ/mol, while glycolysis itself required 82-98 kJ/mol as activation energy, depending somewhat on experimental conditions. Up to 100 attomol of saccharin per bacterial cell was observed. It was concluded that the cytomembrane of S. mutans was involved in mediating the inhibitory effects of saccharin by an antiport of saccharin into cells in exchange for lactate.

Chromatography, High Pressure Liquid↗
PubMed2004

Different functional roles of T1R subunits in the heteromeric taste receptors.

The T1R receptors, a family of taste-specific class C G protein-coupled receptors, mediate mammalian sweet and umami tastes. The structure-function relationships of T1R receptors remain largely unknown. In this study, we demonstrate the different functional roles of T1R extracellular and transmembrane domains in ligand recognition and G protein coupling. Similar to other family C G protein-coupled receptors, the N-terminal Venus flytrap domain of T1R2 is required for recognizing sweeteners, such as aspartame and neotame. The G protein coupling requires the transmembrane domain of T1R2. Surprisingly, the C-terminal transmembrane domain of T1R3 is required for recognizing sweetener cyclamate and sweet taste inhibitor lactisole. Because T1R3 is the common subunit in the sweet taste receptor and the umami taste receptor, we tested the interaction of lactisole and cyclamate with the umami taste receptor. Lactisole inhibits the activity of the human T1R1/T1R3 receptor, and, as predicted, blocked the umami taste of l-glutamate in human taste tests. Cyclamate does not activate the T1R1/T1R3 receptor by itself, but potentiates the receptor's response to l-glutamate. Taken together, these findings demonstrate the different functional roles of T1R3 and T1R2 and the presence of multiple ligand binding sites on the sweet taste receptor.

Amino Acid Sequence↗
PubMed2006

The intake of intense sweeteners - an update review.

Studies on the intakes of intense sweeteners in different countries published since the author's previous review in 1999 indicate that the average and 95th percentile intakes of acesulfame-K, aspartame, cyclamate and saccharin by adults are below the relevant acceptable daily intake (ADI) values. Fewer data are available for the newer sweeteners, sucralose and alitame, and because they are recent introductions to the market very low intakes were reported in those countries where they were available at the time of the intake study. Overall there has not been a significant change in the intakes of sweeteners in recent years. The only data indicating that the intake of an intense sweetener could exceed its ADI value were the 95th percentile intakes of cyclamate in children, particularly those with diabetes. This sub-group was identified as having high intakes of cyclamate in 1999, and recent studies have not generated reliable intake data to address this possibility.

Adult↗
PubMedDate not supplied

Potential intake of intense sweeteners in Brazil.

A survey of intense sweetener intakes was carried out in the winter of 1990 and summer of 1991 in Brazil. Data on the potential intake of the intense sweeteners aspartame, cyclamate and saccharin were generated, based on a representative sample of 673 individuals who completed a questionnaire designed to collect information on demographic details and habitual usage of sweetener-containing food and drinks. The respondents were randomly chosen among intense sweetener consumers living the cities of Campinas, São Paulo and Curitiba, Paraná. Potential daily intakes by individuals were calculated for each sweetener by combining each person's consumption of sweetener-containing food and beverages with information generated by the determination of the concentrations of the sweeteners used in these products. The data showed that 72% of the studied population consumed saccharin, 67% cyclamate and 40% aspartame. The main reasons alleged for the use of intense sweeteners were weight-control diet (36%), diabetes (35%) and weight loss (23%). Table-top sweeteners were the major source of sweeteners, followed by soft drinks. The median daily intake of aspartame, cyclamate and saccharin represented approximately 2.9, 15.5, and 16-4% of the corresponding ADI, respectively. Diabetics in general had a much higher intake within the studied population.

Adult↗
PubMed1999

Taste qualities of solutions preferred by hamsters.

Molecules of diverse chemical structure are sweet to humans and several lines of evidence (genetic, physiological, behavioral) suggest that there may be distinct sweet perceptual qualities. To address how many perceptual categories these molecules elicit in hamsters (Mesocricetus auratus), we studied patterns of generalization of conditioned taste aversions for seven sweeteners: 100 mM sucrose, 320 mM maltose, 32 mM D-phenylalanine, 3.2 mM sodium saccharin, 16 mM calcium cyclamate, 10 mM dulcin and 32 mM sodium m-nitrobenzene sulfonate. Each stimulus was preferred versus water in two-bottle intake tests and stimulated the chorda tympani nerve. For each of seven experimental groups the conditional stimulus (CS) was a sweetener and for the control group the CS was water. Apomorphine.HCl was injected i.p. after a CS was sampled and, after recovery, test stimuli (TS) were presented for 1 h daily. The intake (ml) of each TS consumed by experimental animals was compared with mean TS intake by the control group. Learned aversions for 18/21 stimulus pairs cross-generalized, resulting in a single cluster of generalization patterns for the seven stimuli. Cross-generalization failures (maltose-cyclamate, maltose-sucrose, cyclamate-NaNBS) may be the consequence of particular stimulus features (e.g. salience, cation taste), rather than the absence of a 'sucrose-like' quality. The results are consistent with a single hamster perceptual quality for a diverse set of chemical structures that are sweet to humans.

Animals↗
PubMed1972

The slowing of gastric emptying by four strong acids and three weak acids.

1. Test meals of 750 ml. water containing a range of concentrations of hydrochloric, nitric, sulphuric, cyclamic (cyclohexylsulphamic), tartaric, L-ascorbic and citric acids were instilled into the stomachs of sixteen healthy subjects.2. The greater the concentration of an acid in the instilled meal, the greater was the volume of meal recovered after a fixed interval.3. For the weak acids, tartaric, ascorbic and citric, the concentrations which gave a recovery of 450 ml., out of the 750 ml. instilled, increased with increase in the molecular weight of the acid.4. For the strong acids, hydrochloric, nitric, sulphuric and cyclamic, the concentrations which gave a recovery of 450 ml., out of the 750 ml. instilled, were approximately equal. These concentrations were less than those for weak acids.5. The strong acids with high molecular weights were slightly more effective in slowing gastric emptying than were those with low molecular weights.6. The approximate equality of effectiveness of nitric, sulphuric and cyclamic acids to hydrochloric acid is attributed to the presence of chloride ion in the duodenal contents. Thus all the strong acids instilled produce an environment of hydrochloric acid around the receptor.7. A model for a duodenal receptor responding to acids is proposed.

Acetates↗
PubMed2006

[Restless legs due to ingestion of 'light' beverages containing saccharine; results of an N-of-1 trial].

OBJECTIVE: To determine whether there was a connection between the complaint of restless legs and the ingestion of artificial sweeteners in a patient with these symptoms after drinking certain 'light' beverages. DESIGN: Randomised, double-blind, placebo-controlled N-of-1 trial with a cross-over design. METHOD: During a period of 48 days, the patient took 4 capsules per day containing either 150 mg of cyclamate, 22.5 mg of saccharine, both sweeteners, or placebo on two successive days. Between each of these 2-day periods there was a 2-day rest period during which no capsules were taken. The hospital pharmacist had prepared the capsules and determined the sequence of the 2-day periods on a random basis. The patient did not know which capsules he was taking. Every day on arising, starting 3 weeks before the trial period, the patient noted the intensity and duration of the symptoms in the late evening and previous night. For this notation he used an 11-point scale, from 0 (= no restless legs) to 10 (= almost total inability to sleep because of restless legs). RESULTS: A score of 1-3 corresponded to mild symptoms that had no effect on the patient's sleep; at a score of 4-6 his sleep was disturbed and at a score of 7-10 the patient hardly slept at all. The patient had symptoms more often while using saccharine or the combination of saccharine and cyclamate than when taking the placebo (4 and 4 versus 2 ofthe 6 nights); moreover, the average score was then statistically significantly higher (5.2 and 5.8 versus 3.3). CONCLUSION: There was a connection between the patient's complaints of restless legs and the use of saccharine, but not the use of cyclamate.

Cross-Over Studies↗
PubMed1988

Alleviation of nickel-induced biochemical alterations by chelating agents.

The effect of 1,4,8,11-tetraazacyclotetradecane (Cyclam), triethylenetetramine (TETA), reduced glutathione (GSH), ethylenediamine tetraacetic acid (EDTA), cyclohexanediamine tetraacetic acid (CDTA), diethylene triamine pentaacetic acid (DTPA), and hydroxyethylenediamine triacetic acid (HEDTA) on the alleviation of nickel-induced biochemical and trace-metal alterations in serum, liver, and kidney of nickel-treated rats was studied. The lipophilic chelating agents Cyclam and TETA exhibited a higher order of effectiveness in alleviating nickel-induced alterations compared to EDTA, CDTA, DTPA, and HEDTA, the hydrophilic chelating agents. The higher efficacy of lipophilic agents may be due to their ability to bind to nickel present in extracellular fluid as well as in intracellular fluid, while the hydrophilic agents may bind only to nickel present in extracellular fluid. Our data also suggest that the efficacy of Cyclam to ameliorate nickel-induced alterations is exceptionally high.

Alanine Transaminase↗
PubMed2000

A CD(4)/T(4) receptor peptide ligand labeled with technetium-99m: synthesis and biological activity.

The octapeptide D-Ala-Ser-Thr-Thr-Thr-Asn-Tyr-Thr-NH(2) ([D-Ala(1)]TNH(2)), an analog of peptide T (H-Ala-Ser-Thr-Thr-Thr-Asn-Tyr-Thr-OH) associated with CD(4)/T(4) receptors involved in human immunodeficiency virus infection, was combined with the chelating polyazamacrocycle 1,4,8,11-tetraazacyclotetradecane (cyclam) to afford the bifunctional ligand cyc-[D-Ala(1)]TNH(2). This was then reacted with [(99m)TcO(4)](-) and Sn(2+) to yield the monocationic complex [(99m)Tc(O)(2)(cyc-[D-Ala(1)]TNH(2))](+). Biological activity of both the cyclam-peptide conjugate and the resulting Tc-99m complex were evaluated by measuring their chemotactic indexes. Results showed that N-cyclam acylation and subsequent labeling with Tc-99m of [D-Ala(1)]TNH(2) were tolerated, and both cyc-[D-Ala(1)]TNH(2) and [(99m)Tc(O)(2)(cyc-[D-Ala(1)]TNH(2))](+) retained the high chemotactic capacity of the original octapeptide. Biodistribution of the Tc-99m complex was carried out in rats. Fast blood clearance and no accumulation in organs of interest were observed.

Animals↗
PubMed2000

Characterization of the Ni(III) intermediate in the reaction of (1,4,8,11-tetraazacyclotetradecane)nickel(II) perchlorate with KHSO5: implications to the mechanism of oxidative DNA modification.

We report the detection and characterization of the Ni(III) intermediates generated by reaction of (1,4,8,11-tetraazacyclotetradecane)nickel(II) perchlorate with KHSO5. Four Ni(III) intermediates can be trapped or detected through variation in Cl- or KHSO5 concentrations. Upon oxidation of [Ni(cyclam)]2+ by 2.5 equiv of KHSO5, deprotonation of the cyclam ligand generates two red Ni(III) species with lambda max = 530 nm and g perpendicular = 2.20 and g parallel = 2.02 or g perpendicular = 2.16 and g parallel = 2.01 for the axial 4-coordinate or 6-coordinate dichloride species, respectively. These forms decay to Ni(II) products via complex ligand oxidation mechanisms. The Ni(III) dichloride species can be reprotonated and subsequently binds to DNA via an outer-sphere interaction as evidenced by the inverted sign of the CD signal near 400 nm. Cumulatively, the results indicate that the Ni(III) center is coordinately saturated under excess chloride conditions but is still able to interact with DNA substrates. This suggests alternative mechanistic pathways for DNA modification by reaction of [Ni(cyclam)]2+ with KHSO5 and possibly other Ni(II) complexes as well.

Circular Dichroism↗
PubMed2003

Solution-state and solid-state structural characterization of complexes of a new macrocyclic ligand containing the 1,5-diazacyclooctane subunit.

The synthesis and characterization of a new constrained tetraazamacrocyclic ligand, 1,4,8,11-tetraazabicyclo[9.3.3]heptadecane (1,11-C(3)-cyclam), is reported. Because of its basicity, this ligand (pK(a) of the protonated form >13.5) requires aprotic solvents for its metalation reactions. Two complexes of this ligand, [Ni(1,11-C(3)-cyclam](OTf)(2) and [Co(1,11-C(3)-cyclam)(NCS)(2)](OTf), have been characterized by single-crystal X-ray crystallography. For the Ni(II) complex, the 1,5-diazacyclooctane (daco) subunit of the ligand is in the chair-boat conformation, whereas that same subunit in the Co(III) complex is in the chair-chair conformation. For the Ni(II) complex, C(12) and H(12a) block one of the coordination sites. The (1)H and (13)C NMR spectra of the Ni(II) complex in D(2)O have very sharp resonances, indicative of low-spin Ni(II). The resonance for H(12a) appears at 4.5 ppm, suggesting an interaction with Ni(II). In acetonitrile, the (1)H and (13)C spectra are broadened, indicative of a low-spin/high-spin equilibrium due to axial coordination by acetonitrile. C(12) experiences the greatest degree of broadening in the (13)C NMR spectrum. Variable-temperature NMR spectroscopy from -70 to +80 degrees C shows no significant change as a function of temperature. The electronic spectrum of the Ni(II) complex (lambda(max) = 449.9 nm) is consistent with steric and electronic factors for this complex.

Alkanes↗
PubMed2003

High-nuclearity metal-cyanide clusters: synthesis, magnetic properties, and inclusion behavior of open-cage species incorporating [(tach)M(CN)3] (M = Cr, Fe, Co) complexes.

The use of 1,3,5-triaminocyclohexane (tach) as a capping ligand in generating metal-cyanide cage clusters with accessible cavities is demonstrated. The precursor complexes [(tach)M(CN)(3)] (M = Cr, Fe, Co) are synthesized by methods similar to those employed in preparing the analogous 1,4,7-triazacyclononane (tacn) complexes. Along with [(tach)Fe(CN)(3)](1)(-), the latter two species are found to adopt low-spin electron configurations. Assembly reactions between [(tach)M(CN)(3)] (M = Fe, Co) and [M'(H(2)O)(6)](2+) (M' = Ni, Co) in aqueous solution afford the clusters [(tach)(4)(H(2)O)(12)Ni(4)Co(4)(CN)(12)](8+), [(tach)(4)(H(2)O)(12)Co(8)(CN)(12)](8+), and [(tach)(4)(H(2)O)(12)Ni(4)Fe(4)(CN)(12)](8+), each possessing a cubic arrangement of eight metal ions linked through edge-spanning cyanide bridges. This geometry is stabilized by hydrogen-bonding interactions between tach and water ligands through an intervening solvate water molecule or bromide counteranion. The magnetic behavior of the Ni(4)Fe(4) cluster indicates weak ferromagnetic coupling (J = 5.5 cm(-)(1)) between the Ni(II) and Fe(III) centers, leading to an S = 6 ground state. Solutions containing [(tach)Fe(CN)(3)] and a large excess of [Ni(H(2)O)(6)](2+) instead yield a trigonal pyramidal [(tach)(H(2)O)(15)Ni(3)Fe(CN)(3)](6+) cluster, in which even weaker ferromagnetic coupling (J = 1.2 cm(-)(1)) gives rise to an S = (7)/(2) ground state. Paralleling reactions previously performed with [(Me(3)tacn)Cr(CN)(3)], [(tach)Cr(CN)(3)] reacts with [Ni(H(2)O)(6)](2+) in aqueous solution to produce [(tach)(8)Cr(8)Ni(6)(CN)(24)](12+), featuring a structure based on a cube of Cr(III) ions with each face centered by a square planar [Ni(CN)(4)](2)(-) unit. The metal-cyanide cage differs somewhat from that of the analogous Me(3)tacn-ligated cluster, however, in that it is distorted via compression along a body diagonal of the cube. Additionally, the compact tach capping ligands do not hinder access to the sizable interior cavity of the molecule, permitting host-guest chemistry. Mass spectrometry experiments indicate a 1:1 association of the intact cluster with tetrahydrofuran (THF) in aqueous solution, and a crystal structure shows the THF molecule to be suspended in the middle of the cluster cavity. Addition of THF to an aqueous solution containing [(tach)Co(CN)(3)] and [Cu(H(2)O)(6)](2+) templates the formation of a closely related cluster, [(tach)(8)(H(2)O)(6)Cu(6)Co(8)(CN)(24) superset THF](12+), in which paramagnetic Cu(II) ions with square pyramidal coordination are situated on the face-centering sites. Reactions intended to produce the cubic [(tach)(4)(H(2)O)(12)Co(8)(CN)(12)](8+) cluster frequently led to an isomeric two-dimensional framework, [(tach)(H(2)O)(3)Co(2)(CN)(3)](2+), exhibiting mer rather than fac stereochemistry at the [Co(H(2)O)(3)](2+) subunits. Attempts to assemble larger edge-bridged cubic clusters by reacting [(tach)Cr(CN)(3)] with [Ni(cyclam)](2+) (cyclam = 1,4,8,11-tetraazacyclotetradecane) complexes instead generated extended one- or two-dimensional solids. The magnetic properties of one of these solids, two-dimensional [(tach)(2)(cyclam)(3)Ni(3)Cr(2)(CN)(6)]I(2), suggest metamagnetic behavior, with ferromagnetic intralayer coupling and weak antiferromagnetic interactions between layers.

Journal Article↗