- Time-dependent transformation routes of perovskites CsPbBr3and CsPbCl3under high pressure
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All-inorganic halide perovskites are prospective materials for diverse applications in photovoltaic and optoelectronic devices. Their high performance is associated with good operational stability, which is the key problem of hybrid organic-inorganic perovskites. However, for these materials only fragmentary information is available on the mechanical robustness and response to external stress, fundamentally important for strain engineering in multilayers, pressure-assisted technologies, and flexible panels applications. Here we show that all-inorganic perovskites CsPbX3 (where X = Cl, Br) undergo various types of pressure-induced transformations, including reversible phase transitions, irreversible chemical reactions reducing the dimensionality of PbX6 frameworks, and amorphization. The transformation routes depend on the mode of the applied stress and are related to the kinetics of transitions to the most stable phases. The slow-kinetics transformations in a moderate pressure range of technological importance, between 0.5 and 1.5 GPa, can require days or even weeks, depending on the sample quality and external stimuli. The pressure-induced narrowing and widening of energy gaps has been explained by the mechanism combining Pb-X bond lengths and PbX6 octahedra tilts with the electronic structure of the crystals.
- Katrusiak, Andrzej,St?hl, Kenny,Szafrański, Marek
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p. 10769 - 10779
(2021/05/14)
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- Ion Exchange of Layered Alkali Titanates (Na2Ti3O7, K2Ti4O9, and Cs2Ti5O11) with Alkali Halides by the Solid-State Reactions at Room Temperature
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Ion exchange of layered alkali titanates (Na2Ti3O7, K2Ti4O9, and Cs2Ti5O11) with several alkali metal halides surprisingly proceeded in the solid-state at room temperature. The reaction was governed by thermodynamic parameters and was completed within a shorter time when the titanates with a smaller particle size were employed. On the other hand, the required time for the ion exchange was shorter in the cases of Cs2Ti5O11 than those of K2Ti4O9 irrespective of the particle size of the titanates, suggesting faster diffusion of the interlayer cation in the titanate with lower layer charge density.
- Ogawa, Makoto,Saothayanun, Taya Ko,Sirinakorn, Thipwipa Tip
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p. 4024 - 4029
(2020/04/08)
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- Soluble diamagnetic model for malaria pigment: Coordination chemistry of gallium(III)protoporphyrin-IX
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The facile axial ligand exchange properties of gallium(III) protoporphyrin IX in methanol solution were utilized to explore self-association interactions by NMR techniques. Structural changes were observed, as well as competitive behavior with the ligands acetate and fluoride, which differed from that seen with the synthetic analogue gallium(III) octaethylporphyrin which lacks acid groups in its side-chains and has less solution heterogeneity as indicated by absorption and MCD spectroscopies. The propionic acid side chains of protoporphyrin IX are implicated in all such interactions of PPIX, and both dynamic metal-propionic interactions and the formation of propionate-bridged dimers are observed. Fluoride coordination provides an unusual example of slow ligand exchange, and this allows for the identification of a fluoride bridged dimer in solution. An improved synthesis of the chloride and hydroxide complexes of gallium(III) protoporphyrin IX is reported. An insoluble gallium analogue of hematin anhydride is described. In general, the interactions between solvent and the metal are found to confer very high solubility, making [Ga(PPIX)] + a useful model for ferric heme species.
- Bohle, D. Scott,Dodd, Erin L.,Pinter, Tyler B. J.,Stillman, Martin J.
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p. 10747 - 10761
(2013/01/15)
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- Internal cation mobility in molten CsCl-NdCl3 system at 1073 K
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CsCl-NdCl3 is the next of binary MCl-NdCl3 systems (M: alkali metal) investigated for determination of relative internal mobilities of cations (bCs, bNd) by countercurrent electromigration method (Klemm's method). The results have been presented as isotherms of internal mobilities of Cs+ and Nd3+ ions on NdCl3 equivalent fraction (yNd). It has been found that internal mobility of cesium cations is higher than neodymium ones in the entire composition range (what is typical for nonsymmetrical MCl-LnCl3 systems (M: Li, Na, K; Ln: La, Nd, Dy)) and decreases with increase of NdCl3 concentration in the melt. Generally, dependence of internal mobility of lanthanide cations in melts with alkali metal chlorides on lanthanide (i.e. its atomic number and concentration) seems strongly related to stability of chloride complex anions of lanthanides in the melt. Investigated systems may be divided into two classes. The first class includes MCl-NdCl3 systems (M: Li, Na) characterized by decrease of bNd with increase of NdCl3 concentration. The second includes KCl-LnCl3 systems (Ln: La, Nd, Dy) and presented here CsCl-NdCl3 system, and is characterized by increase of bLn with concentration of Ln3+ cation. The dependence of bNd on NdCl3 concentration at 1073 K was fitted (as for other systems) by a simple equation of the form: bLn = bLn0 + a (1 - yLnC l3)2, where bLn0 is the internal mobility of Ln3+ cations in pure molten LnCl3, a the difference between internal mobility of Ln3+ cations in pure molten LnCl3 and infinitely diluted LnCl3 in molten alkali metal chloride (extrapolated), and yLnC l3 is the equivalent fraction of LnCl3.
- Zab?ocka-Malicka, Monika,Ciechanowski, Bart?omiej,Szczepaniak, W?odzimierz,Gawe?, Wies?aw
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p. 3409 - 3413
(2010/06/21)
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- Effect of residual stress on the optical properties of CsCl thin films
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Large band gap alkali halides are known to have interesting optical properties. Though expected to be transparent in nature, defects in the crystal structure results in alkali halides having colors. The defects gives rise to new energy levels in the band structure, called color centers. Defects are easily generated on film fabrication and hence study of alkali halides promise to be interesting. In this manuscript we report the optical properties of cesium chloride (CsCl) thin films. We have correlated the optical properties of the films with the lattice size of the polycrystalline films, thus highlighting the strong relationship between the structure and optical properties of alkali halide films.
- Kumar, Kuldeep,Arun,Ravi Kant, Chhaya,Mehra,Makinistian,Albanesi
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p. 163 - 169
(2010/06/18)
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- An improved method for product separation in metathetical reactions and its demonstration for the synthesis of anhydrous cesium salts
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In conventional metathetical reactions, product separation is based on solubility product differences, and the resulting products are often impure and require purification by recrystallization. A new approach to product separation is described that relies on the formation of an unstable, volatile by-product, such as NH4+CH3O-. This method provides very pure and anhydrous products in high yield and was demonstrated successfully for the syntheses of anhydrous cesium salts.
- Haiges, Ralf,Christe, Karl O.
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p. 1717 - 1718
(2008/10/08)
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- Absolute rate data for halogen atom-abstraction reactions of ground state atomic caesium, Cs(6 2S1/2) determined by time-resolved laser-induced fluorescence [Cs(7 2P3/2 - 6 2S1/2); λ = 455.5 nm] Following pulsed irradiation
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Absolute rate data are reported for reactions of ground state atomic caesium, Cs(62S1/2), with a wide range of allcyl chlorides and bromides at elevated temperatures following the broad band pulsed generation of the heavy alkali atom from CsI vapour in the presence of the halogenated reactants and excess helium buffer gas. Cs(6 2S1/2) was monitored by laser-induced fluorescence (LIF) in the time-domain using the shorter wavelength component of the Rydberg doublet transition at λ = 455.5 nm [Cs(7 3P3/2 - 6 2S1/2)]. The LIF signals were captured in digital form and subject to computerised analysis. The following second-order rate constants are reported for reaction at essentially single elevated temperatures: kR/cm3 molecule-1 s-1 CH3Cl (6.7 ± 0.1) × 10-12 (860 K); C3H7Cl (8.7 ± 0.1) × 10-12 (855 K); C4H9Cl (1.1 ± 0.1) × l0-11 (855); C5H11Cl (8.2 ± 0.1) × 10-12 (855 K); C6H13Cl (3.9 ± 0.1) × 10-12 (855 K); C7H15Cl (4.5 ± 0.1) × 10-12 (856 K); C3H7Br (1.7 ± 0.1) × 10-11 (855K); C4H9Br (1.2 ± 0.1) × 10-11 (856K); C5H11Br (1.5 ± 0, 1) × 10-11 (855K); C6H13Br (5.9 ± 0.1) × 10-12 (856 K); C7H15Br (5.9 ± 0.1) × 10-12 (856K). With the exception of CH3Cl, these represent a new body of absolute rate data for atomic caesium reported by any-method. All the reactions reported here are exothermic though values of the appropriate thermochemistry cannot be accurately assigned in many cases as, whilst these may be sensibly estimated, the bond dissociation energies are not fully established. The rate data for the reaction of this alkali atom, characterised by a low ionisation potential, are mostly compared with absolute rate data for the lighter but heavy atomic rubidium, Rb(5 2S1/2), which has also a low ionisation potential. The diffusional behaviour of Cs(6 1S1/2) in He and Kr are also reported in this study.
- De Silva,Husain
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p. 775 - 789
(2007/10/03)
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- Heats of solution/substitution of Tl+, Rb+, K+, Br-, I- in crystalline CsCl from heats of solid phase transition by differential scanning calorimetry
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Measurements of the change in heat (enthalpy) of transition in crystalline CsCl effected by the presence of guest ions K+, Rb+, Tl+, Br-, I- using differential scanning calorimetry are reported. The n
- Secco,Secco
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p. 1669 - 1675
(2008/10/08)
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- Cocrystallization of Radioiodine Compounds from the Gas Phase
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The study of the behavior of (137)Cs(131)I in the presence of MCl (M = NH4(1+), K(1+), Ag(1+), and Cu(1+)) in the water vapor-gas phase showed that CsI aerosols are localized in the MCl matrix owing to both agglomeration cocrystallization [(137)Cs(131)I-MCl systems (M = K(1+), Ag(1+), NH4(1+))] and agglomeration capture [(137)Cs(131)I-CuCl system]. The main advantage of the first process is formation of crystalline globules encapsulating radioiodine in their bulk, which prevents transformation of radioiodine into elemental iodine and methyl iodine.
- Kulyukhin, S. A.,Mikheev, N. B.,Kamenskaya, A. N.,Melikhov, I. V.,Rumer, I. A.,Novichenko, V. L.
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p. 580 - 585
(2008/10/08)
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- Saturation vapor pressure over CsMnCl3 at high temperatures
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The saturation vapor pressure over the binary CsCl-MnCl2 system was measured by the boiling-point method. The saturation vapor pressure was described by the equation logp = (-9244 ± 33)/Τ + (10.726 ± 0.026) over the temperature range from 1150 to 1500 K. The enthalpy (176.9 kJ/mol) and entropy [109.5 J/(mol K)] of evaporation and the normal boiling point of CsMnCl3 (1616 K) were determined. An equation of the temperature dependence of the vapor pressure over solid CsMnCl3 was obtained.
- Kostenko,Kritskaya,Moisov,Burylev
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p. 849 - 851
(2007/10/03)
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- Polyhalogenated monoheteroborane anion compositions
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The present invention provides compounds comprising a polyhalogenated heteroborane anion of the formula RaZBbHcFdXe(OR'')f-1, and a method for producing the same. Specifically, the present invention provides compounds comprising a polyfluorinated monocarborane anion.
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- Studies with the rhenacarborane Cs[Re(CO)3(η5-7,8-C2B9H 11)]: Surprising reactivity with a range of metal ligand fragments
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The rhenacarborane salt Cs[Re(CO)3(η5-7,8-C2B9H 11)] (1) has been synthesized in excellent yield using a new procedure. Treatment of CH2Cl2 solutions of 1 with [RuCl2(PPh3)3] yields the exo-closo complex [Re(CO)3(η52,3,10-(μ-H) 3-exo-{RuCl(PPh3)2}-7,8-C2B 9H8)] (2a). In this molecule a [RuCl(PPh3)12]+ moiety is exopolyhedrally bound via three B - H - Ru bonds to a closo-3,1,2-ReC2B9 system. An X-ray diffraction study revealed that one of these agostic interactions utilizes a β-B-H bond in the coordinating CCBBB face of the cage, while the source of the remaining two B - H - Ru bonds is in the 65 belt. The anion of salt 1 also binds exopolyhedral [Rh(PPh3)2]+ and [Rh{Fe(η-C5H4PPh2)2}] + fragments in the complexes [Re-(CO)3(η5-5,10-(μ-H)2-exo-(RhL 2)-7,8-C2B9H9)] (L2 = (PPh3)2 (3a), {Fe(η-C5H4PPh2)2} (3b)). Reaction of 1 with the salts [M(CO)2(THF)(η-C5H5)] [BF4] (M = Fe, Ru) and [Fe(CO)2(THF)-(η-C5Me5)][BF4] gives the complexes [Re(CO)3(η5-n-(μH)-exo-{M(CO) 2(η-C5R5)}-7,8-C2B 9H10)] (M = Fe, R = H, n = 10 (4a); M = Ru, R = H, n = 10 (4b); M = Fe, R = Me, n = 10 (4c), 9 (4d)) with isomers 4c and 4d formed as an inseparable mixture. An X-ray structural study on 4b revealed that there was no Re-Ru bond and that an exro-[Ru(CO)2(η-C5H5)]+ fragment is bound to the rhenacarboranyl anion by a single unsupported B - H - Ru interaction with an unusually long B - Ru distance (2.695(13) A?). The compounds [ReM(μ-10-H-η5-7,8-C2B9H 10)-(CO)3(PPh3)] (M = Cu (5a), Ag (5b)) were isolated from the reaction of 1 with sources of the fragments [M(PPh3)]+ (M = Cu, Ag). X-ray structure determinations of both species 5 revealed the presence of direct Re - M (M = Cu, Ag) connectivities bridged by carborane β-B - H - M interactions. In solution the complexes 5 are highly dynamic on the NMR time scale, even at low ( - 90°C) temoeratures.
- Ellis, Dianne D.,Jelliss, Paul A.,Stone, F. Gordon A.
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p. 4982 - 4994
(2008/10/08)
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- Thermally induced changes in the oxidation state of cerium(IV): A study of carbonato and chloro complexes
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Cesium hexachlorocerate(IV), Cs2CeCl6 (I) and sodium pentakis(carbonato)cerate(IV), Na6Ce(CO3) 5·12H2O (II) have been investigated in air by simultaneous TG/DTA, FTIR and XRD in order to follow the oxidation state of cerium during their mermal treatment. The thermal decomposition of the hexachloro compound (I) is accompanied by a double change in the oxidation state of cerium. First, in an inner reduction-oxidation reaction, chlorine is evolved and a Cs2CeCl5 phase is obtained. The immediately suiting oxidation of this Ce(III) species caused various phase transitions in the CeCl3-CsCl system formed. The presence of Cs3CeCl 6 above 400°C can also be assumed and finally this phase also oxidizes into CeO2 with the formation of CsCl as by-product. In the case of the pentacarbonato complex (II), no Ce(III) species were detected. The final products of its decomposition were CeO2 and Na 2CO3.
- Madarasz,Leskelae,Pokol,Niinistoe
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p. 1347 - 1355
(2008/10/08)
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- [Rh(7-SPh-8-Me-7,8-C2B9H10)(PPh3)2]: A new rhodacarborane with enhanced activity in the hydrogenation of 1-alkenes
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Hydrogenation of 1-hexene is eight times faster with the rhodacarbonate complex 1 than with [RhCl(PPh3)3]. The sulfur atom bound to the open face factors the interaction of the rhodium center with the more active B-H vertices situated on this face.
- Teixidor,Flores,Vinas,Kivekas,Sillanpaa
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p. 2251 - 2253
(2008/10/09)
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- A New Route to Alkali Metal Aluminum Hydrides MAlH4 with M = Na, K, Rb, Cs and Structural Features for The Whole Family with M = Li to Cs.
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MAlH4 with M = Na, K, Rb and Cs were prepared in toluene or hexane from an exchange reaction between LiAlH4 and an halide of the corresponding metal dissolved in the medium as Ziegler-type complex with triethylaluminum. The best process involves the equimolar complexes MF-AlEt3 with fluorides. The four MAlH4 were quantitatively obtained with a purity > 99% (wt). RbAlH4 and CsAlH4 have the same barite-type structure as KAlH4 (orthorhombic, Z = 4), with parameters (?, .+-..002) a:b:c : 9.253:5.950:7.599; 9.981:6.075:7.953, respectively.
- Bastide, J. P.,Hajri, J. El,Claudy, P.,Hajbi, A. El
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p. 1037 - 1048
(2008/10/09)
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- Diastereomeric 5R,6S-6-(1R-hydroxyethyl)-2-(cis-1-oxo-3-thiolanylthio)-2-penem-3-carboxylic acids
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Diastereomeric 5R,6S-6-(1R-hydroxyethyl)-2-(1S-oxo-3R-thiolanylthio)-2-penem-3-carboxylic acid and 5R,6S-6-(1R-hydroxyethyl)-2-(1R-oxo-3S-thiolanylthio )-2-penem-3-carboxylic acid, and pharmaceutically-acceptable salts and in vivo hydrolyzable esters thereof, useful as systemic antibacterial agents; and intermediates and processes which are useful in the said synthesis of said diastereoisomers.
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- Intermediates for 2-(1-oxo-3-thiolanyl)-2-penem antibiotics
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Process and intermediates for the conversion of 3R,4R-4-acetoxy-3-[1R-1-(silyloxy)ethyl]-2-azetidinones to antibacterial 5R,6S-6-(1R-1-hydroxyethyl)-2-(1-oxo-3-thiolanylthio)-2-penem-3-carboxylic acids, and the pharmaceutically-acceptable salts and pivaloyloxymethyl esters thereof.
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- Reactions of the trisulfur trinitride anion, S3N3-, with halogens and other electrophilic substrates
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The reactions of the trisulfur trinitride anion, S3N3-, with halogens (Cl2, Br2, I2), AsF5, SOCl2, SO2Cl2, S2Cl2, COCl2, CS2, Me3SiCl, and Ph2PCl have been investigated.In all cases these reactions gave mixtures of known sulfur-nitrogen compounds.Thus the halogens react with S3N3- to give mainly S4N4, S4N3+X- (X=Br, Cl), (SN)x, and S3N3X3 (X=Cl), while AsF5 oxidizes S3N3- to S4N4*AsF5.The major products of the reaction of S3N3- with SOCl2 or SO2Cl2 were S4N4, S4N3+Cl-, and (for SOCl2 only) S3N2O2.S3N2Cl was the main product of the reaction of S3N3- with S2Cl2, whereas COCl2 yielded (SN)x in addition to S3N2Cl and S4N4.Carbon disulfide reacts with S3N3- to give S4N2, S4N4, and CNS-.The cyclophosphathiazenes, (Ph2PN)(SN)2, 1,3- and 1,5-(Ph2PN)2(SN)2, in addition to (Ph2PN)x (x=3, 4), (Ph2PN)3*HCl and (Ph2PN)2NSCl were isolated from the reactions of Ph2PCl with S3N3- in various molar ratios.The latter reaction represents a useful alternative synthesis of the 1,5-isomer of the eight-membered ring (Ph2PN)2(SN)2.
- Chivers, Tristram,Rao, M. N. Shudheendra
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p. 1957 - 1962
(2007/10/02)
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- Polycyclic macrocyclic compounds
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Novel polycyclic macrocyclic compounds having four tertiary nitrogen bridgehead atoms and six bridging chains, each of which have not more than twelve directly connecting atoms between each pair of bridgehead nitrogens, said bridging chains being hydrocarbon chains and hetero-substituted hydrocarbon chains having at least one hetero connecting atom selected from the group consisting of oxygen, sulfur, and nitrogen, at least two of said chains being hetero substituted. When admixed with a compatible cation-donor compound, the polycyclic macrocyclic compounds form stable cation-containing macrocyclic complexes which, in turn, can be conveniently dissociated by addition of acid or a quaternizing acid. The novel polycyclic macrocyclics are valuable for use in the same way and for the same purposes as chelating agents. The polycyclic macrocyclic compounds are prepared by condensation reactions utilizing high dilution techniques, e.g. by condensing a monocyclic macrocyclic having secondary nitrogen bridgeheads with a substituted hydrocarbon di-carbonyl halide followed by reduction of the resulting lactam or, alternatively, by condensing a monocyclic macrocyclic having secondary nitrogen bridgeheads with a substituted hydrocarbon dihalide (or di-sulfonate).
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