SYNTHESIS, OPTICAL AND SENSORIAL PROPERTIES OF A NEW CALIX[4]ARENE-BASED OLIGO (3,6-CARBAZOLE ETHYNYLENE)

Barata, P.D.a_{; Costa, A.I.}a_{; Prata, J.V.}a

a_{ISEL, Inst Super Engn Lisboa, Área Departamental Engenharia Química, 1959-007 Lisboa,}

Portugal

Fonte: Livro de Resumos do XXII Encontro Nacional da Sociedade Portuguesa de Química, Braga, Portugal 03 a 06 de Julho, 2011

ISBN: 978-989-8124-08-1

Tipo de Documento: Proceeding Paper

Resumo: Research in the area of conjugated polymers has attracted significant interest recently in view of their exciting prospects for application in a range of electronic devices. Polycarbazoles have been studied for more than 30 years. Taking advantage of readily available monomers and the wide variety of side chains added to the nitrogen atom, 3,6- disubstituted carbazoles were particularly investigated.

This work presents the results on the synthesis and photophysical properties of a novel fluorescent calix[4]arene-based oligo(3,6-carbazole ethynylene) (CALIX-OCE) having side- chain O-tripropyl-calixarene units, which was primarily designed for sensing chemistry.

The CALIX-OCE here reported was prepared by a Sonogashira-type cross-coupling reaction of a single bridged double calix[4]arene possessing a diiodo functionality (1) and 3,6-diethynyl-9-propyl-9H- carbazole (2), with catalytic amounts of PdCl2(PPh3)2 and CuI in toluene/NEt3 at 35ºC

(Scheme 1).

The dark orange oligomer was obtained in 37% after purification and the GPC analysis showed a monomodal distribution with a weight-average molecular weight of 8450 gmol-1 (Mw/Mn =1.5). The oligomer has a considerable fluorescence (F= 0.13, CHCl3, nitrogen-

deareated equilibrated solution, room temperature, front-face illumination) and showed a great stability toward photobleaching. CALIX-OCE was evaluated as a sensing material for the detection of a series of nitroaromatic compounds (NACs) currently used as explosives. Using nitrobenzene (NB), 2,4-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT) and picric acid (PA) as analytes, it was pleasantly found that this oligomer shows an excellent behavior as a solution chemosensor, as evaluated by a Stern-Volmer analysis. The quenching efficiencies follow the order PA >> TNT > DNT >NB as should be expected for a photoinduced electron transfer mechanism of quenching.

TRENDS IN PROPERTIES OF PARA-SUBSTITUTED 3-

(PHENYLHYDRAZO)PENTANE-2,4-DIONES

Kopylovich, M.N.a; Mahmudov, K.T.a; Silva, M.F.C.G. daa,b; Martins, L.M.D.R.Sa,c_;

Kuznetsov, M.L.a; Silva, T.F.S.a; Silva, J.J.R. F.daa; Pombeiro, A.J.La

a_{Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, TU, Lisbon, 1049-001}

Lisbon, Portugal

b_{Universidade Lusófona de Humanidades e Tecnologias, ULHT Lisbon, 1749-024 Lisbon,}

c_{ISEL, Inst Super Engn Lisboa, Departamento de Engenharia Quimica, P-1959-007 Lisbon,}

Portugal

Fonte: Journal of Physical Organic Chemistry, Volume 24, Issue 9, pages 764-773, September 2011

DOI: 10.1002/poc.1824

Editor: John Wiley & Sons, Ltd. Tipo de Documento: Article Área Científica: Chemistry

Resumo: Trends between the Hammett's σp and related normal , inductive σI, resonance σR,

negative and positive polar conjugation and Taft's σp° substituent constants and the

distance, δN H NMR chemical shift, oxidation potential (Ep/2°x, measured in this

study by cyclic voltammetry (CV)) and thermodynamic parameters (pK, ΔG0, ΔH0 and ΔS0) of the dissociation process of unsubstituted 3-(phenylhydrazo)pentane-2,4-dione (HL1) and its

para-substituted chloro (HL2), carboxy (HL3), fluoro (HL4) and nitro (HL5) derivatives were

recognized. The best fits were found for σp and/or in the cases of , δN H and Ep/2°x,

showing the importance of resonance and conjugation effects in such properties, whereas for the above thermodynamic properties the inductive effects (σI) are dominant. HL2 exists in the

hydrazo form in DMSO solution and in the solid state and contains an intramolecular H-bond with the distance of 2.588(3) Å. It was also established that the dissociation process of HL1–5 is non-spontaneous, endothermic and entropically unfavourable, and that the increase in

the inductive effect (σI) of para-substitutents ( H <  Cl <  COOH <  F <  NO2) leads

to the corresponding growth of the distance and decrease of the pK and of the changes of Gibbs free energy, of enthalpy and of entropy for the HL1–5 acid dissociation process. The

electrochemical behaviour of HL1–5 was interpreted using theoretical calculations at the

DFT/HF hybrid level, namely in terms of HOMO and LUMO compositions, and of reactivities induced by anodic and cathodic electron-transfers.

V, RE, FE, CO, NI, CU AND ZN COMPLEXES BEARING 2,2,2-TRIS(1- PYRAZOLYL)ETHYL METHANESULFONATE SCORPIONATES. APPLICATION AS CATALYSTS FOR THE BAEYER-VILLIGER OXIDATION OF KETONES UNDER MILD CONDITIONS

Alegria, E.C.B.A.a,b_{; Silva, T.F.S.}a_{; Silva, M.F.Guedes da}a,c_{; Martins, L.M.D.R.S}a,b_;

Pombeiro, A.J.L.a

a_{Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, TULisbon, 1049-001,}

Lisboa, Portugal

b_{ISEL, Inst Super Engn Lisboa, Área Departamental de Engenharia Química, P-1959-007}

Lisbon, Portugal

c_{Universidade Lusófona de Humanidades e Tecnologias, ULHT Lisbon,}

Campo Grande 376, 1749-024, Lisboa, Portugal

Fonte: Proceedings of the 5th EuCheMS Conference on Nitrogen Ligands in Coordination Chemistry, 2011

Conferência: 5th _{EuCheMS Conference on Nitrogen Ligands in Coordination Chemistry,}

Granada, Spain, 4-8 September, 2011 Tipo de Documento: Proceeding Paper

Resumo: In pursuit of our recent work on the coordination chemistry of scorpionate ligands towards different metal centres,[1-4] we focused our attention on functionalized tris(pyrazolyl)methane type ligands with a high hydrophilic nature, such as CH3SO2OCH2C(pz)3, obtained by substitution at the acidic methine hydrogen of HC(pz)3.

Moreover, the coordination chemistry of these types of scorpionates has only been reported scarcely,and our work aims, in part, to provide a contribution towards the development of this still underveloped area of research. Hence, we prepared various V(V), Re(III), Fe(II), Co(II), Ni(II), Cu(II) and Zn(III) complexes bearing such ligands, i.e. [MCln{CH3SO2OCH2C(pz)3}]

{n = 2 for M=V, Re, Fe,Co, Ni, Cu and Zn(II); n=3 for Me = Re} and [VOCl2{CH3SO2OCH2C(pz)3}].

All compounds have been characterized by IR, far-IR, elemental analysis and NMR.

The catalytic activity of these new complexes for the Baeyer-Villiger oxidation of a series of cyclic (4-,5-,6-membered rings) as well as acyclic ketones into the corresponding lactones and esters, using hydrogen peroxide as oxidant, is also reported. Redox potencial-structure relationships will be studied based on cyclic voltammetry (CV) technique.

Física

A NMR APPROACH TO UNDERSTAND WATER BEHAVIOUR ON CHITOSAN/