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Accueil > Séminaires > Archive des séminaires d’Utinam > 2015

Nicolas Mercier

Bipyridinium based Materials : From Halometalate Viologen Hybrids to Highly Luminescent Bismuth Complexes and Photo- and/or Thermochromic Porous Coordination Polymers

jeudi 9 avril 2015, 16h00

salle 018N, bâtiment N

Nicolas MERCIER, Laboratoire MOLTECH - Anjou, Université d’Angers

Résumé :

Some aspects of the chemistry of organic-inorganic hybrids based on bipyridinium units -also called
viologens- (N,N’-disubstituted-4,4’-bipirydinium or N-substituted-4,4’-bipyridinium) will be discussed.

(1) In this first part, the hybrids which will be described are based on viologen cations and halometalate anions.
 [1]
 [2]
 [3]
On one hand, we will illustrate the templating effect of methylviologen
dication which has stabilized the rare MX5 (M = BiIII, SbIII, X = Cl, Br, I) inorganic chain of transconnected
octahedra, leading to a new fascinating family of ferroelectrics.[1] On the other hand, we will show how the photochromic properties of a series of viologen (V2+) chlorobismuthate hybrids
(V)(2n+2)/2[Bi2nCl8n+2] (n=1, 2, 3), which are due to an electron-transfer process from the anionic unit to the electron-acceptor bipyridinium unit, are related to several key parameters (interactions at the
organic-inorganic interface, nature of V2+, size of the inorganic oligomer, Cl/V ratio..).[2]
(2) The discovery of highly luminescent complexes or Coordination Polymers (CPs) based on Bi3+ or Pb2+ and bipyridinium ligands of N-oxide type [4] (N-oxide-4,4’(2,2’)-bipyridinium (bp4mo and
bp2mo) and N,N’-dioxide-4,4’-bipyridinium (bp4do)), with solid state Quantum Yields up to 85% for (TBA)[BiBr4(bp4mo)], will be described. The origin of the photoluminescence as well as the
high QYs will be discussed at the light of specific measurements (lifetime, low temperature studies,…), DFT calculations and crystal structures analysis.
(3) In this last part, our recent investigations for stabilizing Porous CPs (PCPs) based on bipyridinium-carboxylate ligands such as [(bp4mc)2Zn5(BDC)4(HCO2)2](solv),
[(bp4mc)4Zn10(BDC)7(OH)2(HCO2)4(H2O)2](solv)x(H2O)2 or [(bp4mc)Cd2(BDC)2(DMF)](solv)x
(bp4mc= N-benzenepcarboxylate-4,4’-bipirydinium ; BDC2- : 1,4-benzenedicarboxylate) will be
presented. Not only ensuring the cationic nature of organic linkers (expected increase of sorption abilities of PCPs), [5] such electron-acceptor electroactive moieties have capabilities to make specific
donor-acceptor interactions with guest molecules, also potentially leading to photo- and/or
thermochromic properties –Figure- (chemical sensor applications).

Figure.
Figure. [(bp4mc)2Zn5(BDC)4(HCO2)2](solv) : one 3D network and photos of crystals showing photochromic behavior (left) and photo of one bicolor crystal (right).

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[2N. Leblanc, N. Mercier, et al, (a) Inorg. Chem. 2010, 49, 5824 ; (b)Cryst. Growth Des. 2011, 11, 2064.

[3N. Leblanc, N. Mercier et al, (a) Chem. Commun. 2013, 49, 10272,

[5Special issue Metal Organic Frameworks : Chem. Soc. Rev. 2012, 112, 673-1268.