نتایج جستجو برای: macrocycle
تعداد نتایج: 1399 فیلتر نتایج به سال:
in this research work, we report the synthesis of macrocyclic diamides from the reaction of diesters and aliphatic diamines in the presence of caesium carbonate. it has been demonstrated that among the carbonate of alkali metals (li2co3, na2co3, k2co3 and cs2co3), cs2co3 appear to be the best catalyst for macrocyclization. diesters with different substitution patterns on the aromatic ring react...
complexes of benzo-15-crown-5 macrocycle with li+ and cs+ ions were investigated by 7li and 133cs nmr in a number of nonoqueous solutions. the resulting 1:1 complex with li+ ion was found to be much more stable than that with cs+ ion. with the exception of pyridine solutions the stabilities of the complexes varied inversely with the gutmann donor number of the solvents. some indirect evidence f...
The one-step reaction of isophthaloyl dichloride with the 2-aminopyridine derivative (methyl 6-aminonicotinate) yields (i) a trimer-based macrocycle (EsIO)(3) and (ii) a tetramer-based macrocycle (EsIO)(4) in modest isolated synthetic yields (total of 25%), together with (iii) longer open-chain oligomers. The macrocyclization relies on the semi-flexible imide hinge formed by reaction of the 2-a...
F430 is the nickel containing tetrapyrrole cofactor of S-methyl coenzyme M methylreductase, the enzyme that catalyzes the final step of methane production by methanogenic bacteria: the reduction of S-methyl coenzyme M (H3CSCH2CH2SO3-) to methane and coenzyme M (HSCH2CH2SO3-). The protein-free F430 obtained from the cytosol of Methanobacterium thermoautotrophicum, strain delta H, exists predomin...
Anthracene-containing tetralactam macrocycles are prepared and found to have an extremely high affinity for squaraine dyes in chloroform (log Ka = 5.2). Simply mixing the two components produces highly fluorescent, near-infrared inclusion complexes in quantitative yield. An X-ray crystal structure shows the expected hydrogen bonding between the squaraine oxygens and the macrocycle amide NH resi...
The macrocyclic bis-naphthalene macrocycle (2,7-BisNP), belonging to the cyclobisintercalator family of DNA ligands, recognizes T-T mismatch sites in duplex DNA with high affinity and selectivity, as evidenced by thermal denaturation experiments and NMR titrations. The binding of this macrocycle to an 11-mer DNA oligonucleotide containing a T-T mismatch was studied using NMR spectroscopy and NM...
Abstract Heteroditopic calix[6]arenes are extensively exploited as synthetic receptors and molecular components of supramolecular threaded interlocked structures. We describe the synthesis two novel calix[6]arene macrocycles, upper rim which is functionalized with either or three phenylthioureido groups. These moieties excellent hydrogen‐bond donors largely affect conformation macrocycle, both ...
An important pathway for functionalization of porphyrin-based organic-inorganic structures is the metalation porphyrins. Recently, porphyrin was demonstrated on different metal oxide surfaces, however, underlying mechanisms regarding role surface morphology, substituted metal, and ligands are still under investigation. Here we address adsorption self-metalation H2TPP a MgO(001) with low-coordin...
The protonation constants of the ligand 3,6,9,16,19,22-hexaazatricyclo[22.2.2.2]triaconta-1(26),11(12),13,24,27, 29-hexaene (L, BPXD) have been determined in water at 25°C by potentiometric procedures and indicate a lower basicity than that corresponding to the analogue ligand with m-xylyl spacers between the diethylenetriamine subunits (BMXD). The crystal structure of a salt of H6L 6+ containi...
Tetraazamacrocyclie complexes of lead and palladium have been synthesized by the template process using the bis(benzil)ethylenediamine precursor. The tetradentate macrocycle (maL) reacts with PbCl(2), PdCl(2) and different diamines in a 1:1:1 molar ratio in methanol to give several solid complexes of the types [Pb(maL)(R)Cl(2)] and [Pd(maL)(R)]Cl(2) (where R = 2,6-diaminopyridine or 1,2-phenyle...
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