Coordination-Driven Self-Assembly of 2D-Metallamacrocycles Using a New Carbazole-Based Dipyridyl Donor: Synthesis, Characterization, and C-60 Binding Study

Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore-560 012, India.
Inorganic Chemistry (Impact Factor: 4.79). 04/2012; 51(8):4817-23. DOI: 10.1021/ic300199j
Source: PubMed

ABSTRACT A new carbazole-based 90° dipyridyl donor 3,6-di(4-pyridylethynyl)carbazole (L) containing carbazole-ethynyl functionality is synthesized in reasonable yield using the Sonagashira coupling reaction. Multinuclear NMR, electrospray ionization-mass spectrometry (ESI-MS), including single crystal X-ray diffraction analysis characterized this 90° building unit. The stoichiometry combination of L with several Pd(II)/Pt(II)-based 90° acceptors (1a-1d) yielded [2 + 2] self-assembled metallacycles (2a-2d) under mild conditions in quantitative yields [1a = cis-(dppf)Pd(OTf)(2); 1b = cis-(dppf)Pt(OTf)(2); 1c = cis-(tmen)Pd(NO(3))(2); 1d = 3,6-bis{trans-Pt(C≡C)(PEt(3))(2)(NO(3))}carbazole]. All these macrocycles were characterized by various spectroscopic techniques, and the molecular structure of 2a was unambiguously determined by single crystal X-ray diffraction analysis. Incorporation of ethynyl functionality to the carbazole backbone causes the resulted macrocycles (2a-2d) to be π-electron rich and thereby exhibit strong emission characteristics. The macrocycle 2a has a large internal concave aromatic surface. The fluorescence quenching study suggests that 2a forms a ~1:1 complex with C(60) with a high association constant of K(sv) = 1.0 × 10(5) M(-1).

  • [Show abstract] [Hide abstract]
    ABSTRACT: The design and self-assembly of novel multipyrene hexagonal metallacycles via coordination-driven self-assembly is described. By employing newly designed 120° dipyridine donor and di-Pt(II) acceptor linkers substituted with pyrene, a variety of tris- and hexakis(pyrene) hexagonal metallacycles with well-defined shape and size were prepared via [3 + 3] and [6 + 6] self-assembly, respectively, under mild conditions in high yields. The structures of these novel metallacycles were well characterized by multinuclear NMR (31P and 1H) spectroscopy, cold-spray ionization time-of-flight mass spectrometry (CSI-TOF-MS), electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS), and elemental analysis. The shape and size of all hexagonal metallacycles were investigated by the PM6 semiempirical molecular orbital method. The preliminary study of their spectroscopic behavior was also carried out. It was found that these pyrene-modified metallacycles displayed different optical behaviors, which might be caused by the structural effects.
    Organometallics 04/2013; 32(9):2536–2545. DOI:10.1021/om301108s · 4.25 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A series of arene ruthenium architectures have been prepared from coordination-driven self-assembly using dinuclear p-cymene ruthenium acceptors and π-donating tetratopic tetrapyridyl–tetrathiafulvalene donor ligands. The synthetic strategy, based on a geometric interaction approach, leads to four electroactive metalla-assemblies, 1–4 (one molecular cube and three metallaplates), that were characterized by NMR, ESI-MS, X-ray diffraction, and cyclic voltammetry. Rationalization of their formation discrepancy was completed by DFT calculations supported by structural features of their constituting TTF and Ru-complex components. Metalla-architectures possessing electron-rich cores (3, cis-4, and trans-4) interact strongly with picric acid (PA) to yield cocrystallized products, PA + metalla-assemblies, confirmed by single-crystal X-ray structure analyses.
    Organometallics 04/2014; 33(7). DOI:10.1021/om401142j · 4.25 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A series of self-assembled “double saddle”-type trinuclear complexes of [Pd3L′3L2] formulation have been synthesized by complexation of a series of cis-protected palladium(II) components with a slightly divergent “E-shaped” non-chelating tridentate ligand, 1,1′-(pyridine-3,5-diyl)bis(3-(pyridin-3-yl)urea (L). The cis-protecting agents L′ employed in the study are ethylenediamine (en), tetramethylethylenediamine (tmeda), 2,2′-bipyridine (bpy), and 1,10-phenanthroline (phen), for 1, 2, 3, and 4, respectively. The crystal structures of [Pd3(tmeda)3(L)2](NO3)6 (2), [Pd3(bpy)3(L)2](NO3)6 (3), and [Pd3(phen)3(L)2](NO3)6 (4) unequivocally support the new architecture. Two of the “double saddle”-type complexes (3 and 4) are suitably crafted with π surfaces at the strategically located cis-protecting sites to facilitate intermolecular π–π interactions in the solid state. As a consequence, six units of the 3 (or 4) are assembled, by means of six-pairs of π–π stacking interactions, in a circular geometry to form an octadecanuclear molecular ring of [(Pd3L′3L2)6] composition. The overall arrangement of the rings in the crystal packing is equated with the traditional Indian art form rangoli.
    Chemistry - A European Journal 11/2014; 21(4). DOI:10.1002/chem.201405255 · 5.93 Impact Factor


Available from
May 21, 2014