Synlett 2004(10): 1779-1783  
DOI: 10.1055/s-2004-830850
LETTER
© Georg Thieme Verlag Stuttgart · New York

Synthesis of an Isocyanate-Functionalized Terpyridine as Building Block for Metallo-Supramolecular Polymers

Richard Hoogenbooma, Philip R. Andresa,b, Guido Kickelbickc, Ulrich S. Schubert*a,b
a Laboratory of Macromolecular Chemistry and Nanoscience, Eindhoven University of Technology and Dutch Polymer Institute, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
Fax: +31(40)2474186; e-Mail: u.s.schubert@tue.nl;
b Center for NanoScience, Ludwig-Maximilians-Universität München, Geschwister-Scholl Platz 1, 80333 München, Germany
c Institute of Materials Chemistry, Vienna University of Technology, Getreidemarkt 9, 1060 Wien, Austria
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Publikationsverlauf

Received 25 May 2004
Publikationsdatum:
15. Juli 2004 (online)

Abstract

An amino-pentyl-functionalized terpyridine was converted to the corresponding isocyanate, which could be crystallized and studied by X-ray diffraction. The isocyanate-functionalized terpyridine was utilized as a reactive building block for the formation of a metal-coordinating polymer by reacting it under mild ­conditions with a hydroxy functionalized poly(THF). GPC characterization and UV-titration proved successful functionalization and complexation. Secondly, the isocyanate building block was successfully utilized for the formation of a metal coordinating ­compound with two different binding moieties as was proven by 1H NMR spectroscopy.

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4′-(5-Isocyanatopentyloxy)-[2,2′;6′,2′′]terpyridine ( 2). To a stirred solution of di-tert-butyltricarbonate (40 mg, 0.15 mmol) in CH2Cl2 (8 mL) at r.t., a solution of 1 (40 mg, 0.12 mmol) was added over a period of 5 min. After 15 min stirring, the solvent was evaporated and the oily residue dissolved in pentane (at r.t.) in order to obtain a sat. solution. Crystallization at -25 °C yielded 2 as colorless crystals (31 mg, 73%). Mp 68 °C. 1H NMR (300 MHz, CDCl3): δ = 1.55-1.78 (m, 4 H, H γ , δ), 1.89 (tt, J = 6.2, 6.5 Hz, 2 H, H β), 3.36 (t, J = 6.5 Hz, 2 H, H ε), 4.25 (t, J = 6.2 Hz, 2 H, H α), 7.33 (ddd, J = 1.5, 4.8, 7.2 Hz, 2 H, H 5,5 ′′), 7.85 (ddd, J = 1.5, 7.2, 8.0 Hz, 2 H, H 4,4 ′′), 8.01 (s, 2 H, H 3 ,5 ), 8.62 (ddd, J = 1.0, 1.5, 8.0 Hz, 2 H, H 3,3 ′′), 8.69 (ddd, J = 1.0, 1.5, 4.8 Hz, 2 H, H 6,6 ′′). 13C NMR (300 MHz, CDCl3): δ = 23.2 (C γ), 28.4 (C δ), 30.9 (C β), 42.9 (C ε), 67.8 (C α), 107.3 (C 5,5 ′′), 121.3 (C 4,4 ′′), 123.8 (C 3,3 ′′), 136.8 (C 3 ,5 ), 149.0 (C 6,6 ′′), 156.1 (C 2,2 ′′), 157.1 (C 2 ,6 ), 167.2 (C 4 ). MALDI-TOF MS (matrix: dithranol): m/z = 335 (MH+). EIMS (70 eV): m/z = 361 (MH+), 695 (di-terpyridine urea + H+). Anal. Calcd for C21H20N4O2 (360.41): C, 69.98; H, 5.59; N, 15.55. Found: C, 70.23; H, 5.34; N, 15.29. Crystallographic data (C21H20N4O2): triclinic, space group P-1, a = 9.5475 (11), b = 10.3815 (11), c = 11.2582 (13) Å, α = 69.366 (2)°, β = 66.798 (2)°, γ = 74.549 (3)°.

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CCDC 234779 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge at www.ccdc.cam.ac.uk/conts/retrieving.html [or from the Cambridge Crystalographic Data Centre, 12, Union Road, Cambridge CB2 1EZ, UK; fax: (internat.)+44 (1223)336033; email: deposit@ccdc.cam.ac.uk].

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Poly(THF)-terpyridine ( 3). Polymerization of tetra-hydrydrofuran (THF) was performed by the addition of methyl triflate (200 µL, 0.84 mmol) to dry THF (50 mL) at r.t. After 45 min stirring, the polymerization was quenched by the addition of 50 mL H2O followed by precipitation of the reaction mixture in H2O (200 mL). The poly(THF) was obtained as a white solid (6.1 g, 63%). GPC [CHCl3: Et3N: i-PrOH (93:5:2), column at 50 °C]: RI-detector: Mn = 11,600 Da; PDI = 1.20.
To a solution of this (dried) poly(THF) (1.0 g, 0.086 mmol) in CHCl3 (25 mL), isocyanato-terpyridine 2 (150 mg, 0.45 mmol) and two drops of dibutyltindilaurate were added. After 16 h stirring at r.t., the solvent was evaporated and the polymer was precipitated from THF into H2O resulting in the functionalized poly(THF) as a white solid (610 mg, 61%). 1H NMR (400 MHz, CDCl3): δ = 1.38-1.95 (m, 280 H, Hβ , γ , δ, OCH2CH 2 ,pTHF), 3.12-3.69 (m, 275 H, H α, OCH 2 CH2,pTHF, OCH 3 ), 4.25 (t, J = 6.0 Hz, 2 H, Hε), 4.62 (t, J = 5.5 Hz, 1 H, NH), 7.32 (br s, 2 H, H5,5 ′′), 7.85 (ddd, J = 1.7, 7.1, 7.1 Hz, 2 H, H4,4 ′′), 8.00 (s, 2 H, H3 ,5 ), 8.62 (d, J = 7.7 Hz, 2 H, H3,3 ′′), 8.68 (d, J = 4.4 Hz, 2 H, H6,6 ′′). Mn,NMR = 9,700 Da.
GPC [CHCl3: Et3N:i-PrOH (93:5:2), column at 50 °C]: RI-detector: Mn = 11,900 Da, PDI = 1.21, UV-detector (290 nm): Mn = 12,100; PDI = 1.19.

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To a solution of tpy-poly(THF) 3 (3.5 mg, 0.36 µmol) in CHCl3 (3 mL), 10 µL aliquots of iron(II)chloride (32.3 mg, 0.255 mmol) in MeOH (100 mL) were added. After each aliquot, an UV-vis spectrum was recorded.

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[5-([2,2";6",2""]Terpyridin-4"-yloxy)-pentyl]-carbamic acid 4-(3,6-di-pyridin-2-yl-pyridazin-4-yl)-butyl ester ( 5). Isocyanato-terpyridine 2 (100 mg, 0.28 mmol) and two drops of dibutyltindilaurate were added to a solution of 3,6-di(2-pyridyl)-4-(1-hydroxybutyl)pyridazine 4 (74 mg, 0.22 mmol) in CHCl3 (25 mL). After 16 h stirring at r.t., the solvent was evaporated and the crude product was purified by column chromatography (Al2O3, eluent: 1% MeOH in CHCl3) resulting in a white compound (113 mg, 77%). Mp 130-131 °C. 1H NMR (400 MHz, CDCl3): δ = 1.55-1.78 (m, 8 H, H tpy, γ , δ + H dpp, β , γ), 1.89 (t, J = 6.0 Hz, 2 H, H tpy, β), 3.04-3.25 (m, 4 H, H dpp, α + H tpy, ε), 4.04 (t, J = 6.0 Hz, 2 H, H dpp, δ), 4.21 (t, J = 6.0 Hz, 2 H, H tpy, α), 4.80 (t, J = 4.9 Hz, 1 H, NH), 7.31 (ddd, J = 1.1, 4.9, 7.7 Hz, 2 H, H tpy,5,5 ′′), 7.38 (ddd, J = 1.1, 3.8, 7.7 Hz, 2 H, H dpp,5,5 ′′), 7.80-7.95 (m, 4 H, H tpy,4,4 ′′ +H dpp,4,4 ′′), 7.98 (s, 2 H, H tpy,3 ,5 ), 8.12 (d, J = 7.7 Hz, 1H, H dpp,3), 8.49 (s, 1 H, H dpd,5 ), 8.59-8.75 (m, 7 H, H tpy,3,3 ′′ + H dpp,3 ′′ + H tpy,6,6 ′′ + H dpp,6,6 ′′). 13C NMR (400 MHz, CDCl3): δ = 23.1 (C tpy, γ), 26.0 (C dpp, γ), 28.5 (C tpy, δ), 29.5 (C tpy, β), 31.4 (C dpp, α), 31.8 (C dpp, β), 40.7 (C tpy, ε), 64.1 (C dpp, δ), 67.8 (C tpy, α), 107.2 (C tpy,5,5 ′′), 121.2 (C tpy,4,4 ′′), 121.6 (C dpp,3 ′′), 123.5 (C dpp,5), 123.7 (C tpy,3,3 ′′), 124.6 (C dpp,3,5 ′′), 125.5 (C dpp,5 ), 136.7 (C tpy,3 ,5 + C dpp,4), 137.0 (C dpp,4 ′′), 142.1 (C dpp,4 ), 148.4 (C dpp,6), 148.8 (C tpy,6,6 ′′), 149.2 (C dpp,6 ′′), 153.3 (C dpp,2 ′′), 155.8 (C dpp,2), 156.1 (C dpp,6 ), 156.6 (C dpp,3 ), 156.8 (C tpy,2,2 ′′), 157.1 (C tpy,2 ,6 ), 158.8 (NCO), 167.0 (C tpy,4 ). MALDI-TOF MS (matrix: dithranol): m/z = 667 (MH+), 689 (MNa+). Anal. Calcd for C21H20N4O2·H2O (666.79 + 18.02): C, 68.40; H, 5.89; N, 16.36. Found: C, 68.47; H, 5.86; N, 16.48.