Charge-Transfer Absorption and Luminescence Spectra of Alkyl Halide Salts of Pyridine<sup>1a</sup>

Brinen, J. S.; Koren, J. G.; Olmstead, Hugh D.; Hirt, R. C.

doi:10.1021/j100895a025

Cited by 24 publications

(4 citation statements)

References 2 publications

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“…bands, centred at l = 294 and 367 nm, that are characteristic for the solutions of this salt in halogenated solvents. 26 The hypsochromic shift of the NMPI bands generates an isosbestic point at l = 293 nm (see Fig. 5) and at l = 305 nm with 3 and 4, respectively.…”

Section: Recognition Of N-methylpyridinium Ion Pairs (Nmpx)mentioning

confidence: 93%

Monotopic and heteroditopic calix[4]arene receptors as hosts for pyridinium and viologen ion pairs: a solution and solid-state study

et al. 2009

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The binding efficiency of a series of monotopic () and heteroditopic () calix[4]arene-based receptors has been evaluated in chloroform solution toward N-methylpyridinium ion pairs using NMR and UV/vis spectroscopic techniques. These experiments provided evidence that, due to a positive cooperative effect, the presence of a phenylurea H-bond donor group on the upper rim of the calix[4]arene macrocycle increases the recognition abilities of the heteroditopic receptors by up to two orders of magnitude with respect to the monotopic receptors. The heteroditopic receptors are also able to form 2:1 host-guest inclusion complexes with dimethylviologen salts both in low polarity solvents and in the solid state. These complexes are stabilized through the cooperation of weak (CH-pi and cation-pi) and strong (hydrogen bonding) intramolecular interactions between the binding domains of the calix[4]arene host and the two ions of the guest ion pair.

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Section: Recognition Of N-methylpyridinium Ion Pairs (Nmpx)mentioning

confidence: 93%

Monotopic and heteroditopic calix[4]arene receptors as hosts for pyridinium and viologen ion pairs: a solution and solid-state study

et al. 2009

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“…For methylpyridinium iodide the observed luminescence was interpreted as charge transfer fluorescence. 3 We have studied the luminescence using a phosphoroscope and verified that the lifetime of the emission is less than 10~3 s. While the position of the emission band for the compound remained unchanged with change in temperature, the intensity of the band gradually diminished as temperature was lowered (Figure 6a). (In the case of methiodides of the diazines more than one emission band was detected.…”

Section: Resultsmentioning

confidence: 80%

Effect of temperature on the charge transfer band of methiodide of some nitrogen heteroaromatics

Bagchi¹,

Chowdhury²

1976

J. Phys. Chem.

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Spectra of methiodides of pyridine and diazines in solution have been studied in the temperature range 50 to -50 °C. The observed blue shift of the charge transfer (CT) band with a decrease in temperature is explained as being due to an increase of solvation of the intimate ion pair. No such shift, however, is observed in the emission studies. The intensity of the CT absorption decreases with a decrease in temperature and this has been attributed to a modification of equilibria between several types of ion pairs and dissociated ions in the solution. A spectrophotometric method (noniterative) has been suggested for the determination of the ionpair dissociation constant (K¿) and emax. Other thermodynamic quantities (AH0 and AS0) have also been determined from such studies.

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“…6d) is barely recognised as a "shoulder" of an intense absorption due to the π-π * transition of the pyridine ring. 63 Contrariwise, both bands are red-shifted upon dilution to 10 −4 M. Such a shift at lower energy was explained as an ion-pair aggregation reduction. The results of the previous experiments indirectly confirmed that the stoichiometry of the binding between the ditopic hosts 4b and c and the series of N-alkylpyridinium guests is strongly affected by aggregation of the ion pair to be bound.…”

Section: Synthesis Of the Ditopic Hostsmentioning

confidence: 95%

“…However, only the two bromides (NMPBr and NOPBr) and iodides (NMPI and NOPI) present in this solvent a non-hidden charge transfer (CT) band exploitable for the titration experiments. 63 Indeed, upon addition of the host solution, such a band usually underwent an intensity damping accompanied by a slight hypsochromic shift. As an example, the two collections of spectra recorded during the titration of NMPI and NMPBr with host 4b are gathered in Fig.…”

Section: Synthesis Of the Ditopic Hostsmentioning

confidence: 99%

Synthesis and recognition properties of calix[4]arene semitubes as ditopic hosts for N-alkylpyridinium ion pairs

et al. 2016

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A series of calix [4]arene semitubes (4a-c) having alkyl bridging spacers of different lengths and flexibilities on their lower rim was synthesised and characterised in solution and in the solid state by 1 H NMR spectroscopy and X-ray crystallography. The binding properties of these novel ditopic hosts toward a series of N-alkylpyridinium ion pairs were investigated in low polar media by 1 H NMR and UV-vis spectroscopy and compared with those of the corresponding calix[4]arene monotopic host 5. These studies showed that in low polar solvents, the calix[4]arene semitubes behave as homoditopic hosts giving rise with N-alkylpyridinium ion pairs to supramolecular adducts of 1 : 2 host-guest stoichiometry.

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Charge-Transfer Absorption and Luminescence Spectra of Alkyl Halide Salts of Pyridine^1a

Cited by 24 publications

References 2 publications

Monotopic and heteroditopic calix[4]arene receptors as hosts for pyridinium and viologen ion pairs: a solution and solid-state study

Monotopic and heteroditopic calix[4]arene receptors as hosts for pyridinium and viologen ion pairs: a solution and solid-state study

Effect of temperature on the charge transfer band of methiodide of some nitrogen heteroaromatics

Synthesis and recognition properties of calix[4]arene semitubes as ditopic hosts for N-alkylpyridinium ion pairs

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Charge-Transfer Absorption and Luminescence Spectra of Alkyl Halide Salts of Pyridine1a

Cited by 24 publications

References 2 publications

Monotopic and heteroditopic calix[4]arene receptors as hosts for pyridinium and viologen ion pairs: a solution and solid-state study

Monotopic and heteroditopic calix[4]arene receptors as hosts for pyridinium and viologen ion pairs: a solution and solid-state study

Effect of temperature on the charge transfer band of methiodide of some nitrogen heteroaromatics

Synthesis and recognition properties of calix[4]arene semitubes as ditopic hosts for N-alkylpyridinium ion pairs

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Charge-Transfer Absorption and Luminescence Spectra of Alkyl Halide Salts of Pyridine^1a