A versatile building block for pyrazole–pyrrole hybrid macrocycles

Katsiaouni, Stamatia; Dechert, Sebastian; Brückner, Christian; Meyer, Franc

doi:10.1039/b614049a

Cited by 15 publications

(11 citation statements)

References 30 publications

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“…Siamese-twin porphyrin 8 was prepared as described in the literature, [13,27] except that the work-up was altered as follows:T he solvent was removed in vacuum from the crude reaction mixture and the residue was flushed through as hort column of basic alumina (Brockmann grade I, 50-200 mm) with THF/CH 2 Cl 2 /EtOAc in the ratio of 10:3:1 as eluent. The first teal-colored fraction was collected and the solvent removed.…”

Section: Methodsmentioning

confidence: 99%

Siamese‐Twin Porphyrin Origami: Oxidative Fusing and Folding

Vogel

Dechert

John

et al. 2015

Chemistry A European J

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Oxidation of a nonaromatic Siamese-twin porphyrin, a pyrazole-containing expanded porphyrin with two porphyrinlike binding pockets, with a stoichiometric amount of the two-electron, two-proton oxidizing agent 2,3-dichloro-5,6-dicyano-1,4-benzochinone led to the formation of a single N(pz) -C(o-Ph) linkage between the pyrazole unit with a neighboring meso-phenyl group, forming a pyrazolo- [1,5-a]indole moiety. Repeated treatment with a second equivalent of the oxidant yielded a doubly N-fused species, involving the second pyrazole moiety. The conversion products were characterized by variable-temperature and multinuclear 1D and 2D NMR spectroscopy. The fusions strongly alter the conformation of the macrocycles, as shown by X-ray diffraction analyses of all three compounds, eventually leading to a folded structure. UV/Vis and NMR-spectroscopic investigations indicated the presence of highly delocalized but nonmacrocycle-aromatic π systems. This behavior of the Siamese-twin porphyrin in response to oxidation is in contrast to the behavior of related all-pyrrole-based expanded macrocycles that switch, by redox processes and protonation, between Hückel and Möbius aromatic states.

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Section: Methodsmentioning

confidence: 99%

Siamese‐Twin Porphyrin Origami: Oxidative Fusing and Folding

Vogel

Dechert

John

et al. 2015

Chemistry A European J

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“…19 F NMR spectra were referenced against C 6 F 6 . Where necessary, assignment of the NMR signals was derived from 2D spectra; abbreviations used in the assignments: py = pyr- [16,17] and 3,5-bis(bromomethyl)-1-(tetrahydropyran-2-yl)pyrazole hydrochloride (8 b), [15] 3,5-bis-(chloromethyl)-1H-pyrazole (11), [13] and 3,4-diethylpyrrole (7 c) [25] were prepared according to literature procedures. All other reagents were commercially available and were used as received.…”

Section: Methodsmentioning

confidence: 99%

“…These aspects make pyrazoles particularly interesting for incorporation into molecular-recognition systems and biomimetic bimetallic complexes. [8,10,11,12] Although a combination of pyrroles and pyrazoles into one ligand framework suggests itself, prior to our recent communication reporting macrocycle 4 a, [13] little was known about such compounds. [14] We attribute the scarcity of information on pyrazole-containing pyrrolic macrocycles to the absence of suitable pyrazole-based building blocks.…”

Section: Introductionmentioning

confidence: 99%

“…[13] The acid-base properties of these compounds are discussed and the scope and limits of these macrocycles in molecular-recognition events are ascertained by using single-crystal diffractometry, and UV/Vis and NMR spectroscopy. As will become evident, the novel macrocycles do not compete, at least not as far as tested, with the anionrecognition abilities of many other pyrrole-based macrocycles.…”

Section: Introductionmentioning

confidence: 99%

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Schiff Base Macrocycles Containing Pyrroles and Pyrazoles

Katsiaouni¹,

Dechert²,

Briñas³

et al. 2008

Chemistry A European J

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A double nucleophilic substitution reaction of 3,5-bis(chloromethyl)pyrazole with pyrroles generates a novel pyrrole-pyrazole hybrid building block, the pyrazole analogue to tripyrrane. Vilsmeier-Haack formylation produces the corresponding dialdehyde, which was used in the formation of a series of nonaromatic Schiff base macrocycles. NMR and UV/Vis spectroscopy and single-crystal diffractometry were used to characterize the novel macrocycles. The solid-state structures of select free bases and protonated members of this class of macrocycles display a range of intra- and intermolecular hydrogen-bonding patterns that suggest their use in molecular-recognition systems. They also contain an acid-sensitive chromophore. Their acid-base and anion-recognition properties were ascertained; alas, only modest anion-selective spectroscopic signatures could be detected by using UV/Vis and (1)H NMR spectroscopy. The macrocycles proved resistant toward oxidation to their aromatic congeners. The pyrrole-pyrazole building blocks presented are potentially useful for the synthesis of a range of pyrazole analogues of all-pyrrole macrocycles.

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“…10 Specifically, assemblies containing aromatic heterocyclic Article ring systems such as pyrimidine, piperidine, pyridine, pyrrole, and pyrazole ligands have been shown to be very efficient metal ion attractors. 11 For example, 2-(methylthio)-4-(pyridin-4-yl)pyrimidine was self-assembled in the presence of both silver and copper ions, creating two different complexes. While both metal ions had affinity toward the ring system; silver ions showed higher affinity and this metal-ligand affinity played a significant role in the formation of supramolecular assemblies that were formed.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of CdS bound pyrazole carboxamide conjugated nanoassemblies and their applications

Hartnett¹,

J²,

Romanelli³

et al. 2014

Mat Express

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In this work, a new family of nanoassemblies were developed by conjugating the pyrazole-based moiety 4-Amino-1-methyl-3-n-propyl-5-pyrazolecarboxamide (AMP) with the chelating agent 1,3-diamino-2-hydroxypropane-N,N,N,N-tetraacetic acid (TTA). By altering the ratio of AMP added, three conjugates were synthesized. Each of those conjugates were self-assembled at varying pH values to promote the growth of higher order supramolecular structures. The results showed that growth was pH dependent as well as dependent on the ratio of AMP to TTA utilized to form the conjugates. While under acidic conditions, primarily nanofibers were observed, under basic conditions, nanovesicles were formed. Due to the chelating ability of the conjugates, CdS nanoparticles were then grown on the assemblies. The hybrid CdS nanoparticle-bound assemblies showed distinct anti-fungal activity as well as cytotoxicty toward HeLa cells. Thus we have developed a new family of supramolecular assemblies with potential applications in biosensors or in environmental monitoring.

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A versatile building block for pyrazole–pyrrole hybrid macrocycles

Cited by 15 publications

References 30 publications

Siamese‐Twin Porphyrin Origami: Oxidative Fusing and Folding

Siamese‐Twin Porphyrin Origami: Oxidative Fusing and Folding

Schiff Base Macrocycles Containing Pyrroles and Pyrazoles

Fabrication of CdS bound pyrazole carboxamide conjugated nanoassemblies and their applications

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