Consequence of presence and absence of π-clouds at strategic locations of designed binuclear Pd(II) complexes on packing: Self-assembly of self-assembly by intermolecular locking and packing

Mili C. Naranthatta, Deepika Das, Debakanta Tripathy, Himansu S. Sahoo, Venkatachalam Ramkumar, Dillip K. Chand

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

Self-assembled binuclear coordination cages of general formula [Pd 2(N-N)2(L)2](X)4, 1a/b-4a/b are prepared by the combination of N,N′-bis(m-pyridyl)urea, L, with a variety of cis-protected palladium(II) components, Pd(N-N)(X)2. The cis-protecting units "N-N" employed for the synthesis of 1-4 are ethylenediamine (en), tetramethylethylenediamine (tmeda), 2,2′-bipyridine (bpy), and 1,10-phenanthroline (phen), respectively. The term "X" stands for nitrate and perchlorate for a and b, respectively. The assemblies are characterized by NMR and electrospray ionization mass spectrometry (ESI-MS) techniques, and in some cases (i.e., 1a, 2b, 3b, 4a, and 4b) the structures are confirmed by single crystal X-ray diffraction. The conformations of bound L in the crystal structures of all the Pd(II) complexes are found to be syn-syn. The influence of the presence and absence of π cloud at the cis-protecting units on the crystal packing has been studied in detail. In the packing of [Pd 2(phen)2L2](NO3)4, 4a, one unit of [Pd2(phen)2L2]4+ is associated with two other units by π-π stacking interactions thus giving a one-dimensional growth as envisioned on the basis of a design principle. In the case of [Pd2(en)2(L)2](NO3) 4, 1a, and [Pd2(tmeda)2(L)2] (ClO4)4, 2b, such packing is not observed due to the absence of π-cloud at the strategic locations, instead notable H-bonding interactions are seen. However, [Pd2(bpy)2(L) 2](ClO4)4, 3b, displays a π-π interactions using only two units of [Pd2(bpy)2(L) 2]4+(ClO4)-.

Original languageEnglish (US)
Pages (from-to)6012-6022
Number of pages11
JournalCrystal Growth and Design
Volume12
Issue number12
DOIs
StatePublished - Dec 5 2012
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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