A picosecond time-resolved study on prototropic reactions of electronically excited 1,5- and 1,8-diaminonaphthalenes in aqueous solution

Takehira, Katsuomi; Sugawara, Yoshiki; Kowase, Susumu; Tobita, Seiji

doi:10.1039/b414725a

Cited by 6 publications

(4 citation statements)

References 34 publications

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“…A possible explanation for the increase in charge in the +2 complexes is the electron‐withdrawing nature of the additional positively charged ‐NH 3 headgroup. A similar behavior was observed by Takehira et al for diaminonaphthalene . The higher charge is most notable for short‐chained species where the positive charges are close together.…”

Section: Discussionsupporting

confidence: 85%

Dependence of collision‐induced dissociation energy on molecular degrees of freedom as a means to assess relative binding affinity in multivalent complexes

Huffman

Williams

Benoist

et al. 2011

Rapid Comm Mass Spectrometry

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In collision-induced dissociation mass spectrometry experiments, the collision energy required for dissociation linearly depends on the degrees of freedom in the precursor ion. The magnitude of the slope of this relationship previously has been shown to qualitatively correlate to the relative binding strength of a noncovalently bound, monovalent complex. The goal of the work presented here is to determine if a similar methodology can be applied for assessing relative binding strengths in multivalent species. We have tested the method on complexes formed from 18-crown-6 and a variety of protonated, primary alkylamines, [C(n)H(2n+1)NH(3)](+) (n=9, 12, 14, 16 and 18) and alkyldiamines, [H(3)NC(n)H(2n)NH(3)](2+) (n=3, 5, 6, 9 and 12), and compared our results with dissociation energies calculated using density functional theory at the B3LYP/6-31G* level. We found that the method correctly assessed the stronger crown ether/headgroup interaction in the two divalent species (1:1 and 2:1 complexes formed from the diaminoalkanes) compared with the weaker interaction in the monovalent species (1:1 complexes formed from mono-aminoalkanes). However, the experimental method could not distinguish between the binding strengths of the two divalent complexes, perhaps because their calculated dissociation energies were quite similar. Our preliminary results suggest that this method could potentially be used for a quick and simple analysis of binding strengths in multivalent species if the binding strengths of the species are significantly different from one another.

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Section: Discussionsupporting

confidence: 85%

Dependence of collision‐induced dissociation energy on molecular degrees of freedom as a means to assess relative binding affinity in multivalent complexes

Huffman

Williams

Benoist

et al. 2011

Rapid Comm Mass Spectrometry

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“…It should be mentioned that the computed PA values for DAN and DMAN, reported in the literature, slightly differ from the experimental ones and depend on the level of calculation. They are as follows (in kJ mol –1 ): 952.8 {MP2/6-31G(d)//HF/6-31G(d,p)}, 959.4 {DFT(B3LYP)/6-31G(d)}, 967.8 {DFT(B3LYP)/6-31G(d,p)}, and 933.2 {DFT(M05-2X)/6-311++G(d,p)}, for DAN, and 1031.2 {HF/6-31G(d)//HF/6-31G}, 1042.0 {MP2/6-31G(d)//HF/6-31G(d,p)}, 1020.1 {MP2/6-31+G(2d,2p)//MP2/6-31G(d)}, 1040.4 {DFT(B3LYP)/6-31G(d)}, 1030.7 {DFT(B3LYP)/6-31+G(d,p)//HF/6-31G(d,p)}, 1026.3 {DFT(B3LYP)/6-311+G(2df,p)//B3LYP/6-31G(d)}, and 1022.6 {DFT(M05-2X)/6-311++G(d,p)} for DMAN.…”

Section: Resultsmentioning

confidence: 99%

Can Nitriles Be Stronger Bases Than Proton Sponges in the Gas Phase? A Computational Analysis

et al. 2015

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DFT calculations have been performed for a series of push-pull nitriles [(R2N)n(X═Y)iC≡N, where i = 0, 1, or 2, n = 1, 2, or 3, R2N = H2N, Me2N, or C4H8N, X = CH, N, or P, Y = CH or N]. The possible protonation N-sites (N-cyano, N-imino, and N-amino) have been examined and their proton affinities (PA) estimated. For all compounds in the series, even for those containing the guanidino, phosphazeno, and diphosphazeno pushing groups, the N-cyano atom is the favored site of protonation. The n-π conjugation strongly decreases the PA value of the pushing amino group in favor of the pulling cyano one. Nitriles with the phosphazeno groups [(R2N)3P═N-P(R2N)2═N and (R2N)3P═N] exhibit the strongest basicity in the series. Some of them (with PA > 1000 kJ mol(-1)) are stronger bases than DMAN, the so-called "proton sponge". Nitriles bearing the guanidino group [(R2N)2C═N] are less basic than those with the phosphazeno group [(R2N)3P═N] but more basic than those with the formamidino group (R2N-CH═N) containing the same substituent R. The N-imino atoms, present in the transmitter group (X═N, X = CH, N, or P), display PA values lower than those of the N-cyano site by more than 30 kJ mol(-1). When proceeding from the unsubstituted derivatives (R = H) to the methylated ones (R = Me), the Me groups at the N-amino atom increase the PA value of the N-cyano site for Me2N-X═Y-C≡N (X, Y = CH or N) by ca. 30-60 kJ mol(-1). For the guanidino and phosphazeno derivatives containing two and three amino groups, respectively, this effect is not additive. The four Me groups for (Me2N)2C═N-C≡N and the six Me groups for (Me2N)3P═N-C≡N increase the PA(N-cyano) values by only 30-50 kJ mol(-1). The C≡N bond lengths of the neutral forms are well correlated with the PA(N-cyano) values.

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“…DAN is a basic matrix and its conjugate acid has lower p K a values (p K a1 ~ 4.6, p K a2 ~ 2.6) than that of 9-AA (p K a − 10.2). 31,38,39 In two recent studies, DAN was used in lipid and small-molecule metabolite research to detect negatively charged ions. 17,40–42 In 2012, DAN was used to analyze lipids (negative ion m / z range of 650–1600) and compared the results to 7 other matrices, including 9-AA.…”

Section: Resultsmentioning

confidence: 99%

A binary matrix for the rapid detection and characterization of small-molecule cardiovascular drugs by MALDI-MS and MS/MS

et al. 2018

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A picosecond time-resolved study on prototropic reactions of electronically excited 1,5- and 1,8-diaminonaphthalenes in aqueous solution

Cited by 6 publications

References 34 publications

Dependence of collision‐induced dissociation energy on molecular degrees of freedom as a means to assess relative binding affinity in multivalent complexes

Dependence of collision‐induced dissociation energy on molecular degrees of freedom as a means to assess relative binding affinity in multivalent complexes

Can Nitriles Be Stronger Bases Than Proton Sponges in the Gas Phase? A Computational Analysis

A binary matrix for the rapid detection and characterization of small-molecule cardiovascular drugs by MALDI-MS and MS/MS

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