Search results for "cyclen"
showing 10 items of 21 documents
CCDC 260690: Experimental Crystal Structure Determination
2006
Related Article: J.J.Schneider, D.Spickermann, C.W.Lehmann, J.Magull, H.-J.Kruger, J.Ensling, P.Gutlich|2006|Chem.-Eur.J.|12|1427|doi:10.1002/chem.200500100
Conformations and coordination schemes of carboxylate and carbamoyl derivatives of the tetraazamacrocycles cyclen and cyclam, and the relation to the…
1998
Abstract This paper discusses and rationalizes the metal coordination pattern of 12- and 14-membered tetraazamacrocyclic carboxylate and carbamoyl ligands based on the cyclen and cyclam framework in light of their acido–basic properties. Structural and protonation data are reviewed in order to illustrate the influence of the free ligand's protonation state and of the pH conditions during the complexation reaction on the final coordination mode of the metallic cations.
Synthesis of a new family of bi- and polycyclic compounds via Pd-catalyzed amination of 1,7-di(3-bromobenzyl)cyclen
2008
Abstract New bicyclic cryptand type compounds are synthesized by reacting 1,7-di(3-bromobenzyl)cyclen with 1 equiv of linear polyamines under dilute conditions using Pd-catalyzed amination. Bis(cyclen) and tris(cyclen) compounds containing linear polyamine linkers between benzylated cyclens are obtained by a similar procedure using different reaction conditions. Cyclization of these species via intramolecular catalytic diamination led to tri- and tetracyclic polyaza compounds.
Application of tris-allyl-DOTA in the preparation of DOTA–peptide conjugates
2006
Abstract The synthesis of tris-allyl-DOTA starting from cyclen and its application in the preparation of DOTA–peptide conjugates is reported. Clinically important conjugates such as DOTA–Tyr3-octreotide (DOTA–TOC), DOTA–Tyr3-octreotate (DOTA–TATE) as well as a DOTA–RGD peptide were synthesized in high yields with Fmoc solid phase peptide synthesis. The final, extremely reliable de-allylation was achieved on solid phase by different methods identifying morpholine/Pd(0) as the most suitable one obtaining all DOTA peptide conjugates in high yields. All DOTA–peptides were purified by reversed phase HPLC and structural identity was proved using MALDI-TOF mass spectrometry.
Micelles as containers for self-assembled nanodevices: a fluorescent sensor for lipophilicity
2008
Potentiometric titrations, fluorescence versus pH titrations, dynamic light scattering and fluorescence polarization anisotropy studies demonstrate that inside the nanodimensioned Triton X-100 micelles, 1-pyrenecarboxylic acid, PCOO-, forms an apical complex with the Zn2+ cation encircled by a lipophilic cyclen ligand and hugely increasing its fluorescence. The ability of the Zn2+-cyclen-PCOO- complex plus its micellar container to act as a fluorescent sensor to evaluate the lipophilicity of molecular species is demonstrated on the fatty acid series CH 3(CH2)xCOOH (x=0-16). At pH 7.4 a decrease in fluorescence is observed on the addition of fatty acids that is directly related to their chai…
Rapid Synthesis of Unsymmetrical Sulforhodamines Through Nucleophilic Amination of a Monobrominated Sulfoxanthene Dye
2014
A transition-metal-free method for the synthesis of N-substituted unsymmetrical sulforhodamine fluorophores from an unusual monobrominated sulfoxanthene dye and primary or secondary amines by direct SNAr-type reactions is presented. The simplicity and effectiveness of this “postamination” procedure were demonstrated through the rapid preparation of a library of multifunctional red-emitting rhodamine analogues. Some of these analogues are equipped with a reactive handle and retain the two water-solubilizing sulfonic acid moieties of the starting halogenated derivative; this makes them ideal candidates for biolabeling applications. The potential utility of this expeditious strategy to finely …
Synthesis and Structural Characterization of a Cyclen-Derived Molecular Cage
2015
Reaction of a tetrafunctionalized cyclen derivative containing four aldehyde groups with an appropriate diamine followed by reduction and demetalation highly efficiently affords a bis(cyclen)-derived molecular cage. Potentiometric investigations show that this compound forms dimetallic complexes with copper(II), with the two metal ions selectively coordinated to the cyclen units. X-ray crystallography indicates that these complexes could give rise to new cascade complexes after incorporation of anions between the metal centers.
BODIPY Dyes Functionalized with Pendant Cyclic and Acyclic Polyamines
2013
The synthesis and characterization of a series of BODIPY derivatives substituted with acyclic and cyclic polyamines, in particular, cyclen and homocyclen, are reported. The 19F NMR, UV/Vis, and fluorescence spectroscopic data of these compounds are discussed. One compound was found to be very selective for CuII ions, which makes it a very promising system for CuII detection.
Pd-catalyzed amination in the synthesis of cyclen-based macrotricycles
2012
Abstract Three approaches to three types of cyclen-based macrotricycles have been elaborated starting from trans-bis(3-bromobenzyl)cyclen. The macrotricycles were synthesized via Pd-catalyzed amination. The first approach employed consecutive macrocyclization and benzylation steps giving a cage-like tricycle. In the second, cyclen amino groups were Boc-protected prior to formation of the second and the third rings. In the third method, macrotricycles were synthesized according to a one-step procedure using diazacrown ethers.
New Insights into the complexation of lead(II) by 1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane (DOTAM): structural, thermodynami…
2007
The lead(II) coordination properties of the tetrapodal ligand DOTAM [1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraaza-cyclododecane] have been investigated both in the solid state and in solution in order to ascertain the stereoactivity of the lone pair and to rationalize the structural effects of a cyclen-based scaffold on the metal uptake kinetics. The crystal structure of the free base shows that the pendant acetamide groups are not equivalent: two are folded over the macrocycle and maintained by an intramolecular hydrogen bond involving an amide hydrogen atom and a neighboring tertiary amine of the cyclen ring, while the other two are extended and point away from the macrocyclic cav…