Table
8
Mass spectral data for terpyridines synthesiseda and
elemental analyses for new compounds
range 10–250 MHz. A suspension of Ludox® in water was used
as the standard, which acts as a scattering sample of τ 0.0 ns.
L1 309 (Mϩ), 231 (Mϩ Ϫ py), 78 (Phϩ). L2 324 (Mϩ), 246 (Mϩ Ϫ py);
HRMS (EI): 324.1374 (Mϩ); calc. for C21H16N4, M: 324.1375. L3 337
(Mϩ). L4 354 (Mϩ), 324 (Mϩ Ϫ NO), 308 (Mϩ Ϫ NO2). L5 334 (Mϩ), 256
(Mϩ Ϫ py). L6 352 (Mϩ), 308 (Mϩ Ϫ NMe2); HRMS (EI): 352.1686
(Mϩ); calc. for C23H20N4, M: 324.1683; found C, 76.71, H, 5.58, N,
16.32; calc. for C23H20N4ؒ0.5H2O: C, 76.43, H, 5.86, N, 15.50%. L7
Acknowledgements
Financial support from the University of Durham and the
Royal Society is gratefully acknowledged. We thank the EPSRC
National Mass Spectrometry Service Centre, Swansea for
recording several high resolution mass spectra. K.W. is a
student of Universität Würzburg, Germany, and was supported
at Durham under the Socrates Exchange Scheme of the
E.U. We should also like to thank Frontier Scientific UK for
samples of boronic acids and our former colleague, Dr
Catherine J. Aspley, for pioneering studies on the terpyridine
boronates, which underpin much of the work reported here.
(using CI) 477 (M ϩ Hϩ). L8 351 (Mϩ), 350 (Mϩ Ϫ H), 335 (Mϩ
Ϫ
CH3), 273 (Mϩ Ϫ py); HRMS: 352.1812 (M ϩ Hϩ); calc. for C24H21N3,
M ϩ Hϩ: 352.1813; found C, 78.95, H, 5.90, N, 11.74; calc. for
C24H21N3ؒH2O: C, 78.00, H, 6.27, N, 11.37%. L9 385 (Mϩ), 307 (Mϩ Ϫ
py). L10 410 (Mϩ), 332 (Mϩ Ϫ py); HRMS: 411.1609 (M ϩ Hϩ); calc. for
C28H18N4, M ϩ Hϩ: 411.1609; found C, 80.24, H, 4.35, N, 13.38; calc.
for C28H18N4ؒ0.5H2O: C, 80.17, H, 4.57, N, 13.36%. L11 430 (Mϩ), 400
(Mϩ Ϫ NO), 384 (Mϩ Ϫ NO2), 352 (Mϩ Ϫ py), 322 (Mϩ Ϫ NO Ϫ py);
HRMS: 431.1501 (M ϩ Hϩ); calc. for C27H18N4O2, M ϩ Hϩ: 431.1508;
found C, 74.46, H, 4.09, N, 12.65; calc. for C27H18N4O2: C, 75.34, H,
4.21, N, 13.02%. L12 428 (Mϩ), 308 (Mϩ Ϫ C6H4NMe2); HRMS:
429.2079 (M ϩ Hϩ); calc. for C29H24N4, M ϩ Hϩ: 429.2079; found C,
75.01, H, 5.43, N, 11.63; calc. for C29H24N4ؒ2H2O: C, 74.98, H, 6.08, N,
12.05%. L13 (using CI) 553 (M ϩ Hϩ). L14 386 (Mϩ), 308 (Mϩ Ϫ py);
HRMS: 387.1610 (M ϩ Hϩ); calc. for C26H18N4, M ϩ Hϩ: 387.1609;
found C, 71.88, H, 5.18, N, 12.03; calc. for C26H18N4ؒ3H2O: C, 70.89, H,
5.49, N, 12.72%. L15 386 (Mϩ), 308 (Mϩ Ϫ py); HRMS: 387.1609 (M ϩ
Hϩ); calc. for C26H18N4, M ϩ Hϩ: 387.1609.
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a Low resolution mass spectral data are provided for all compounds and
were obtained by electron ionisation, except where stated otherwise.
Accurate mass data are provided for those compounds which have not
been reported previously, and were obtained by electrospray ionisation,
except where marked EI, indicating electron ionisation. Elemental
analyses are given for new compounds; small deviations from calculated
values are consistent with the presence of retained water molecules,
confirmed by the 1H NMR spectra in anhydrous CDCl3.
24 h. The progress of the reaction could be monitored readily
by thin layer chromatography on alumina, eluant 70% hexane–
30% ethyl acetate, allowing consumption of the 4Ј-bromo-
terpyridine (Rf = 0.6) and formation of product (Rf = 0.2) to be
followed. (Gas chromatography was also suitable, except for
the terpyridines carrying amino functionality). After complete
consumption of starting material, the solvent was removed
under reduced pressure, and the crude residue dissolved in a
mixture of dichloromethane and water (25 mL of each). The
organic layer was separated, washed with dilute aqueous
sodium hydroxide (0.1 M, 3 × 30 mL) and dried over anhydrous
potassium carbonate. Removal of solvent led to a green-brown
residue which, after recrystallisation from ethanol, led to the
1
required product as a colourless solid (497 mg, 80%). H and
13C NMR data are given in Tables 2–5.
The ‘reverse’ coupling procedure, involving the reaction
of the terpyridine-4-boronate ester, or terpyridine-4-phenyl-
boronate ester, with an aryl halide, was carried out in the same
way, using a 10% excess of the boronate. Those reactions which
employed 4Ј-triflate-terpyridine in place of 4Ј-bromoterpyr-
idine were also performed similarly, but using tetrahydrofuran
as the solvent in place of dimethoxyethane.
Characterisation data for the terpyridines are given in Tables
2–5 (nuclear magnetic resonance) and Table 8 (mass spectra
and elemental analyses).
Absorbance and emission spectra and lifetimes
UV–visible absorbance spectra were recorded using a Bio-Tek
Instruments Uvikon-XS spectrometer using quartz cuvettes of
1 cm pathlength. Steady-state emission spectra were recorded in
1 cm pathlength cuvettes, using an Instruments S.A. Fluromax
equipped with a Hamamatsu R928 photomultipler tube;
spectra were corrected for the wavelength dependence of the
detector. Fluorescence lifetimes were measured using an
Instruments S.A. Fluorolog τ-3 instrument, by global fitting of
the demodulation and phase shift of the emission, following
excitation with sinusoidally-modulated light over the frequency
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Soc., Chem. Commun., 1995, 65.
1680
J. Chem. Soc., Perkin Trans. 2, 2002, 1669–1681