Effect of styryl substituents introduced into the periphery of pyrazinoporphyrazine macrocycle on the spectral and luminescence properties of complexes

A synthesis is reported for a new pyrazinoporphyrazine complex containing eight styryl fragments on the periphery of the macrocycle, namely, zinc tetrakis-2,3-{5,6-bis[(E)-2-(4-methylphenyl)vinyl]pyrazino}-porphyrazine. The introduction of styryl substituents into the macrocycle leads to a significant bathochromic shift of the Q-band in the electronic absorption spectrum and to an increase in the fluorescence quantum yield. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 2, pp. 118–123, March–April, 2007.     

The 15N NMR spectra of macrocyclic compounds containing the ferrocene unit

The synthesis of a ¹⁵N enriched macrocycle containing the ferrocene unit is descibed, and the ¹⁵N NMR spectra of the macrocycle and those of its complexes with some metallic cations are reported.     

A Strategy Utilizing a Recyclable Macrocycle Transporter for the Efficient Synthesis of a Triazolium‐Based [2]Rotaxane

A general synthesis of triazolium‐containing [2]rotaxanes, which could not be accessed by other methods, is reported. It is based on a sequential strategy starting from a well‐designed macrocycle transporter which contains a template for dibenzo‐24‐crown‐8 and a N‐hydroxysuccinimide (NHS) moiety. The sequence is: 1) synthesis by slippage of a [2]rotaxane building‐block; 2) its elongation at its NHS end; 3) the delivery of the macrocycle to the elongated part of the axle by an induced translational motion; 4) the contraction process to yield the targeted [2]rotaxane and recycle the initial transporter.     

Synthesis,Structural Characterization,and Reductive Cleavage of an Oxygen-Containing Naphthyl Macrocycle

A small macrocycle comprising ether-bridged naphthyl units was prepared in a two-step synthesis. Single-crystal X-ray diffraction of two polymorphs are reported, one of which showed multiple C−H⋅⋅⋅π_naphthyl interactions of a solvent molecule in the cavity of the macrocycle. Chemical reduction led to C−O bond cleavages accompanied by a Z/E isomerization. The resulting twofold negatively charged (E)-1,2-bis(2-naphthyl)ethylene fragment was isolated as its potassium salts. Electronic characterization revealed a singlet ground state, and a marked distortion of the central ethylene unit was observed upon electron uptake.     

Fumarate of (S,S)-alpha,alpha'-bis(trifluoromethyl)-1,8-anthracenedimethanol. A chiral macrocycle for the Diels-Alder reaction with cyclopentadiene

The synthesis and structural study of the fumarate of (S,S)-alpha,alpha'-bis(trifluoromethyl)-1,8-anthracenedimethanol by NMR spectroscopy are reported. The conformational study of the 13-membered macrocycle is presented. The cited alcohol is assayed as a chiral auxiliary in a Diels-Alder reaction with cyclopentadiene, and after methanolysis, provides the norbornene derivative with high enantioselectivity.     

Synthesis and structure of a stabilized 10-membered cyclic enediyne

The synthesis and structure of an acetal protected 10-membered cyclic enediyne-1,2-diol rac-10 is reported. The conformational constrain of the unsaturated macrocycle by the acetal protection group prevents the thermal cyclization reaction of the endiyne during synthesis and purification.     

Synthesis and two-photon absorption property of phenylacetylene macrocycles

The first synthesis of phenylacetylene macrocycle with large two-photon absorption cross section is reported.     

30]heptaphyrin(1.1.1.1.1.0.0): an aromatic expanded porphyrin with a 'figure eight' like structure

The synthesis, characterization, and X-ray structure of a heptapyrrolic macrocycle, [30]heptaphyrin(1.1.1.1.1.0.0) is reported; despite showing aromatic features, it exhibits a 'figure eight'-like structure in the solid state.     

Strained cyclophane macrocycles: impact of progressive ring size reduction on synthesis and structure

The synthesis, X-ray crystal structures, and calculated strain energies are reported for a homologous series of 11- to 14-membered drug-like cyclophane macrocycles, representing an unusual region of chemical space that can be difficult to access synthetically. The ratio of macrocycle to dimer, generated via a copper catalyzed azide-alkyne cycloaddition macrocyclization in flow at elevated temperature, could be rationalized in terms of the strain energy in the macrocyclic product. The progressive increase in strain resulting from reduction in macrocycle ring size, or the introduction of additional conformational constraints, results in marked deviations from typical geometries. These strained cyclophane macrocyclic systems provide access to spatial orientations of functionality that would not be readily available in unstrained or acyclic analogs. The most strained system prepared represents the first report of an 11-membered cyclophane containing a 1,4-disubstituted 1,2,3-triazole ring and establishes a limit to the ring strain that can be generated using this macrocycle synthesis methodology.     

Binuclear organometallic ruthenium complexes of a Schiff base expanded porphyrin

The synthesis of binuclear organometallic ruthenium complexes of an expanded porphyrin-type macrocycle is reported; pyrrolic hydrogen bonding donors were found to interact with ancillary ligands in the primary coordination sphere and to stabilize coordinated dioxygen in an eta(2)-fashion.     

Bambus[n]urils: a new family of macrocyclic anion receptors

A recently discovered anion receptor is jointed by three related macrocycles differing in the number of glycoluril units and type of substitution. The synthesis is carried out in nonpolar solvents compared to aqueous media used in the case of the original macrocycle. The size of macrocycle is controlled by a template. A hexameric macrocycle with benzyl substitution binds halide anions with an affinity exceeding 10(9) M(-1) while a tetrameric analog does not bind any of the investigated anions.     

Template synthesis of a huge macrocycle by olefin metathesis using easily accessible [Pt(PEt(3))(2)] templates

We have reported the template synthesis of a 90-membered macrocycle by olefin metathesis. The macrocycle 7 was prepared by an initial six-oxidative-addition reaction of 2 by [Pt(PEt(3))(4)]. The definite structure of a six-oxidative product was confirmed by the crystal structure. The coordination of 2,6-bis(hex-5-enyloxy)pyridine to 3 led to the hexacationic aryl complex of type 4. The metathesis of olefin-substituted pyridine with Grubbs catalyst ([PhCH==RuCl(2)(Cy(3)P)(2)]) formed the expected macrocycle 5. The olefin metathesis reaction was formed under high dilution to suppress intermolecular olefin metathesis polymerization. The detachment of the newly formed macrocycle 6, followed by reduction to alkane macrocycle 7 by using palladium on charcoal and hydrogen led to a huge macrocycle. The mild and easy access of the template protocol opens a host of potential subsequent transformations toward the construction of a variety of macrocycles.     

Phenylene‐Bridged Core‐Modified Planar Aromatic Octaphyrin: Aromaticity,Photophysical and Anion Receptor Properties

The synthesis of a planar expanded meso porphyrin with an intramolecular para‐phenylene‐bridged core is reported. The planarity of the octaphyrin macrocycle was confirmed by single‐crystal X‐ray structural analysis, in which the bridged para‐phenylene unit deviated by 27° from the mean macrocyclic plane. Spectroscopic analyses and theoretical calculations suggested that the macrocycle was Hückel aromatic and followed a major [34 π] single‐conjugation pathway, which indicated that the bridging para‐phenylene unit was not involved in the macrocyclic conjugation. Analysis of the photophysical properties of this system by steady‐state absorption/fluorescence spectroscopy and transient absorption spectroscopy revealed moderate enhancement in the parameters of the octaphyrin as compared to its non‐bridged octaphyrin congeners, which was attributed to the planarity and rigidity of the macrocycle as imposed by the bridging para‐phenylene unit. Preliminary anion‐binding studies revealed that the protonated macrocycle bound selectively with chloride ions through N?H???Cl hydrogen‐bonding interactions.     

A convergent synthesis of Hexahomotriazacalix

A new, convergent synthesis of hexahomotriazacalix[3]arenes 1a-e is described. The key transformation in this synthesis involves the coupling of the triamines 4a-d with 2, 6-bis(chloromethyl)-4-methylphenol 5 and results in the formation of the hexahomotriazacalix[3]arenes 1a-d in 90-95% yield. The triamines 4a-d were constructed by the one-pot reaction of monochloroaldehyde 3 and a primary amine followed by reduction to yield the triamines 4a-d in 50-55% yield. Deallylation of macrocycle 1d was accomplished by palladium catalysis to obtain the N-unsubstituted macrocycle 1e, which has the potential to be a precursor to a variety of N-substituted hexahomotriazacalix[3]arenes.     

Synthesis of readily modifiable cyclodextrin analogues via cyclodimerization of an alkynyl-azido trisaccharide

A convergent strategy for the synthesis of beta-cyclodextrin analogues is reported, utilizing preferential cyclodimerization of an azido-alkyne trisaccharide via Cu(I)-catalyzed [3 + 2] dipolar cycloaddition of the alkyne and azide functional groups. The resultant oligosaccharide macrocycle retains the binding propensity of cyclodextrins, as demonstrated by the similar ANS association constants measured for macrocycle 1 and beta-cyclodextrin. This new synthetic strategy opens up new avenues for modular preparation of functionally diverse cyclodextrin analogues that are otherwise inaccessible.     

Synthesis of a new 24-membered tetramide macrocycle and X-ray crystal structure determination

The synthesis and characterization of a new 24-membered tetramide macrocycle (6) related to Leigh's macrocycles and catenanes is reported. The replacement of p-xylylenediamine (Leigh) by m-xylylenediamine (this work) strongly modifies the geometry and properties of the new macrocycle. NMR spectroscopy (in DMSO?d₆ solution) and X-ray crystallography have been used to characterize compound 6. The structural features in the crystal (conformational aspects and H-bonding) have been discussed comparatively to two similar macrocycles NEWHIJ and UJUNOC.     

Synthesis, characterization, and luminescence properties of a new series of Eu3+-containing macrocycles

The synthesis and structural characterization of a series of neutral Eu(3+)-containing macrocyclic complexes, Eu(4)-Eu(7), are reported. The synthetic pathway herein allows for the size and functionality of the macrocycle to be tailored in one step from a common precursor (N,N' '-bis(p-isothiocyanatobenzylcarbamoylmethyl)diethylenetriamine-N,N'N' '-triacetic acid, (3) in high yield. The macrocyclic ligands 4-7 have within their structure a bis-amide derivative of diethylenetriaminepentaacetic acid (DTPA) functioning as the europium chelate that is bridged through thiourea groups by either a butyl (4), hexyl (5), octyl (6), or m-benzyl (7) linker. The two thiourea groups were designed into the host macrocycle to serve as hydrogen-bond donors to potential guest molecules that may alter the luminescence properties of the parent macrocycle. Characterization of the luminescence of Eu(4)-Eu(7) reveals an antenna effect from the ligand, and the luminescence lifetime data reveals the presence of one coordinated water molecule in aqueous solution.     

Synthesis of cyclic dimeric methyl morpholinoside—a common synthetic precursor to cyclic dinucleotide analogs

An eight-step synthesis of cyclic dimeric methyl morpholinoside (c-di-MM), a common synthetic precursor to a number of cyclic dinucleotide analogs is reported. The synthesis of c-di-MM proceeds through a morpholine monomer prepared from readily available inexpensive starting materials and culminates with a key macrolactamization reaction to provide the macrocycle in 15% overall yield.     

Shape-persistent macrocycle with a self-complementary recognition pattern based on diacetylene-linked alternating hexylbenzene and perfluorobenzene rings

The synthesis and characterization of a shape-persistent macrocycle, consisting of alternating electron rich and electron poor sub-units as a self-complementary recognition pattern, is reported, and its increased tendency to form dimer complexes in solution is demonstrated and discussed.     

Rapid Total Synthesis of Cyclic Lipodepsipeptides as a Premise to Investigate their Self‐Assembly and Biological Activity

A rapid and efficient total synthesis is reported for the cyclic lipodepsipeptide pseudodesmin A. This member of the Pseudomonas viscosin group is active against Gram‐positive bacteria and features self‐assembling properties. A conserved serine residue within the lactone macrocycle is exploited for initial immobilization on 2‐chlorotrityl chloride resin through ether formation with the side‐chain alcohol. Subsequent elongation proceeds through Fmoc solid‐phase peptide synthesis, including automated incorporation of the enantioselectively synthesized (R)‐3‐hydroxydecanoic acid lipid tail. Following esterification to generate the incipient lactone bond, the macrocycle is formed by on‐resin head‐to‐tail macrolactamization and cleaved from the resin to give the desired compound in good purity. The short and efficient synthesis route allows rapid generation of analogues by facile variation of both the peptide and lipid moieties with good control of epimerization while maximizing automation. Synthesis of the pseudodesmin A enantiomer yields identical self‐assembly and biological activity to that observed for the natural compound, showing that activity is not mediated by chiral interactions. A D ‐Asn8 analogue developed en route retains self‐assembly, but loses activity. The synthesis strategy should be generally applicable for the rapid generation of analogues from various cyclic lipodepsipeptide groups, allowing an investigation of their self‐assembling properties and structure–activity relationships.