Article

First synthesis of an expanded calixpyrrole

Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas, United States
Tetrahedron Letters (Impact Factor: 2.39). 12/1997; 38(49):8443-8444. DOI: 10.1016/S0040-4039(97)10275-1

ABSTRACT The synthesis of the first expanded calixpyrrole: a calix[5]arene-capped calix[5]pyrrole 2 has been achieved using p-tert-butylcalix[5]arene pentamethyl ketone 1 as a template. (C) 1997 Elsevier Science Ltd.

1 Follower
 · 
35 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: The syntheses and spectral/structural characterization of ansa-ferrocene-incorporated normal calixphyrins and core-modified calixpyrroles and calixphyrins are reported. Acid-promoted dehydrative condensation of 1,1′-bis(dimethylpyrrolylmethyl)ferrocene and 2,5-bis(dimethylhydroxymethyl)thiophene/furan yielded ansa-ferrocene-based core-modified calixpyrroles, while acid-catalyzed dehydrative condensation of 1,1′-bis(diphenylpyrrolylmethyl)ferrocene with the aryl aldehydes and 2,5-bis(phenylhydroxymethyl)thiophene followed by DDQ oxidation resulted in the formation of ansa-ferrocene-appended normal and core-modified calixphyrins, respectively. The newly synthesized macrocycles were characterized by FAB-MS, NMR, and UV–vis spectral analyses and finally confirmed by single-crystal X-ray structural analysis. All these studies clearly revealed the introduction of ferrocene in the main framework of the corresponding macrocycles in an ansa-type way. The core-modified calixpyrroles adopt a 1,3-alternate conformation, while the corresponding calixphyrins maintained partial planarity along the tripyrrin plane due to the presence of meso sp2 carbon and generated curved staircase conformation. In addition to the intramolecular hydrogen-bonding interactions, calixphyrins generate self-assembled dimers, one- and two-dimensional supramolecular assemblies through intermolecular hydrogen bonding in the solid state.
    Organometallics 05/2012; 31(11):4166–4173. DOI:10.1021/om300004m · 4.25 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The chemistry of porphyrin analogues, fully or partially conjugated macrocyclic systems that contain pyrroles but are not naturally occurring substances, is discussed from an historic perspective. Key developments that led to the emergence of this area as a separate discipline within the generalized porphyrin lexicon are highlighted with a view to allowing the reader to understand better the current state of the art in the field.
    Journal of Porphyrins and Phthalocyanines 06/2000; 4(4):331-336. · 1.36 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Two new benzoTTF-annulated calix[n]pyrroles (n = 5 and 6) were synthesized via a one-step acid catalyzed condensation reaction and fully characterized via single crystallographic analyses. As compared to the known tetra-TTF annulated calix[4]pyrrole, which is also produced under the conditions of the condensation reaction, the expanded calix[n]pyrroles (n = 5 and 6) are characterized by a larger cavity size and a higher number of TTF units (albeit the same empirical formula). Analysis of the binding isotherms obtained from UV-Vis spectroscopic titrations carried out in CHCl3 in the presence of both anionic (Cl−, Br−, I−, CH3COO−, H2PO4−, and HSO4−) and neutral (1,3,5-trinitrobenzene (TNB) and 2,4,6-trinitrotoluene (TNT)) substrates revealed that as a general rule the calix[6]pyrrole derivative proved to be the most efficient molecular receptor for anions, while the calix[4]pyrrole congener proves most effective for the recognition of TNB and TNT. These findings are rationalized in terms of the number of electron rich TTF subunits and NH hydrogen bond donor groups within the series, as well as an ability to adopt conformations suitable for substrate recognition, and are supported by solid state structural analyses.
    Chemical Science 07/2012; 3(9):2685-2689. DOI:10.1039/C2SC20636F · 8.60 Impact Factor