Constructing polymeric proton donor and proton acceptor in layer-by-layer structure for efficient proton transfer in PEMFC

2016 ◽  
Vol 41 (8) ◽  
pp. 4765-4772 ◽  
Author(s):  
Chalanda Meemuk ◽  
Suwabun Chirachanchai
Keyword(s):  
Proton Transfer ◽  
Layer Structure ◽  
Proton Donor ◽  
Proton Acceptor ◽  
Layer By Layer

Packing-dependent photochromism: the case of photoinduced intramolecular proton transfer in 6-(2′,4′-dinitrobenzyl)-2,2′-bipyridine

2004 ◽  
Vol 60 (3) ◽  
pp. 343-349 ◽  
Author(s):  
Pance Naumov ◽  
Yuji Ohashi
Keyword(s):  
Crystal Structure ◽  
Proton Transfer ◽  
Nitro Group ◽  
Pyridine Ring ◽  
Intramolecular Proton Transfer ◽  
Proton Donor ◽  
Methanol Solution ◽  
Proton Acceptor ◽  
Methylene Group ◽  
Rotational Freedom

A new photoactive monoclinic polymorph (γ-form) of 6-(2′,4′-dinitrobenzyl)-2,2′-bipyridine was obtained from an acetone–methanol solution. The crystal structure was compared with those of two polymorphs reported previously (photoactive orthorhombic α-form and photoinactive monoclinic β-form) and with structures of related nitrobenzylpyridines to explain the relation between the structure and photochromism. The comparison of the reaction cavities around the reactive pyridyl–benzyl–nitro fragment among the polymorphs and related nitrobenzylpyridines revealed that a crucial factor for photochromic activity is the rotational freedom of the ortho-nitro group in their crystals and its accessibility from the proton–donor and proton–acceptor sites. This is because the ortho-nitro group should rotate around the N—C bond to transfer a proton from the methylene group to the N atom of the pyridine ring.

A theoretical study of 3,5-diazido-1,2,4-triazole: the role of the hydrogen bonding interaction in stabilizing the molecular system

2014 ◽  
Vol 92 (9) ◽  
pp. 896-903 ◽  
Author(s):  
Junqing Yang ◽  
Xuedong Gong ◽  
Guixiang Wang
Keyword(s):  
Hydrogen Bonding ◽  
Proton Transfer ◽  
Density Functional ◽  
Molecular System ◽  
Polarizable Continuum Model ◽  
Proton Donor ◽  
Proton Acceptor ◽  
Good Thermal Stability ◽  
The Stability ◽  
Dynamics Simulations

3,5-Diazido-1, 2, 4-triazole (DATZ) is a compound that has a good thermal stability and can be used to produce high energetic ionic salts. The conformations of DATZ were searched by the molecular dynamics simulations and optimized by the molecular mechanics and dispersion-corrected density functional theory methods. The dimer and trimer of DATZ were constructed from the most stable monomer. The hydrogen bonding interactions, which were found to be critically important in increasing the stability of the dimer and trimer, were investigated with the help of the natural bond orbital and the quantum theory of atoms in molecules analyses. The changes in thermodynamic functions, stabilization interaction energies, and hydrogen-bonding energies show that the trimer is most likely the existing form of DATZ. The intramolecular, intermolecular, and water catalytic proton transfer processes were simulated to investigate the proton transfer mechanism. The intermolecular transfer process requires the lowest activation energy (42.56 kJ mol−1) and is the most likely process of proton transfer. DATZ is not only a proton acceptor but also a proton donor. Its weak acidity was quantified as pKa = 10.16. The solvation energy estimated using the conductor-like polarizable continuum model in water is the largest (−99.96 kJ mol−1), revealing that DATZ is more stable in water than in another seven solvents.

scholarly journals Base-enhanced catalytic water oxidation by a carboxylate–bipyridine Ru(II) complex

2015 ◽  
Vol 112 (16) ◽  
pp. 4935-4940 ◽  
Author(s):  
Na Song ◽  
Javier J. Concepcion ◽  
Robert A. Binstead ◽  
Jennifer A. Rudd ◽  
Aaron K. Vannucci ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Proton Transfer ◽  
Water Oxidation ◽  
Proton Acceptor ◽  
Half Time ◽  
X Ray ◽  
X Ray Crystallography ◽  
Buffer Base ◽  
Electron Proton Transfer ◽  
C Nmr

In aqueous solution above pH 2.4 with 4% (vol/vol) CH3CN, the complex [RuII(bda)(isoq)2] (bda is 2,2′-bipyridine-6,6′-dicarboxylate; isoq is isoquinoline) exists as the open-arm chelate, [RuII(CO2-bpy-CO2−)(isoq)2(NCCH3)], as shown by 1H and 13C-NMR, X-ray crystallography, and pH titrations. Rates of water oxidation with the open-arm chelate are remarkably enhanced by added proton acceptor bases, as measured by cyclic voltammetry (CV). In 1.0 M PO43–, the calculated half-time for water oxidation is ∼7 μs. The key to the rate accelerations with added bases is direct involvement of the buffer base in either atom–proton transfer (APT) or concerted electron–proton transfer (EPT) pathways.

A Potentiometric Study on Proton-Transfer Equilibria and Cationic Conjugation in Pyridine N-Oxide Systems in Acetone and Methanol

1996 ◽  
Vol 49 (9) ◽  
pp. 931 ◽  
Author(s):  
L Chmurzynski ◽  
E Kaczmarczyk ◽  
M Nesterowicz ◽  
G Wawrzyniak ◽  
Z Warnke
Keyword(s):  
Proton Transfer ◽  
Equilibrium Constants ◽  
Proton Donor ◽  
Heterocyclic Amines ◽  
Transfer Reactions ◽  
Oxide Systems ◽  
Experimental Systems ◽  
Proton Transfer Reactions ◽  
Potentiometric Titration Method

The potentiometric titration method has been used to study the equilibria of cationic in sytems formed by substituted pyridine N-oxides in the polar, non-aqueous solvents acetone and methanol. For comparison, the systems with trimethylamine N-oxide as a representative of aliphatic amine N-oxides and pyridine representing parent heterocyclic amines were also studied. The cationic heteroconjugation constants, i.e. the equilibrium constants for conjugation reactions between free and protonated N-bases leading to the formation of unsymmetric BHB'+ cations, were determined in experimental systems with and without proton transfer. It was found that there were significant differences in the values of the cationic heteroconjugation constants determined in these two acid-base systems. The proton-transfer reactions limit and even preclude the determination of the cationic heteroconjugation constants. On this basis it was concluded that the heteroconjugation constants should be determined in systems without proton transfer. In such systems, in the amphiprotic solvent methanol, cationic heteroconjugation was ascertained in all substituted pyridine N-oxide systems, the values of heteroconjugation constants being relatively low (logarithms of their values of the order of 2-2.5), and only negligible in systems involving trimethylamine N-oxide. A more pronounced tendency towards cationic heteroconjugation of the [OHO]+ type was observed in the aprotic protophobic acetone, where heteroconjugation constants were determined for all amine N-oxide systems studied including those containing protonated trimethylamine N-oxide as a proton donor. However, the values of the cationic heteroconjugation constants were found to be, in methanol likewise, relatively low (log KBHB'+ of the order of 2-3). On the contrary, a greater extent of cationic heteroconjugation equilibria was observed in methanol than in acetone in the case of systems containing pyridine, i.e. [NHO]+ type bridges formed by amine N-oxides and heterocyclic amines. In methanol the heteroconjugation constants turned out to be determinable for all such systems studied (logarithms of the equilibrium constants being of the same order as for N-oxide systems), whereas in acetone the hetero constants were indeterminable for all systems.

An interesting 1,4,2,5-dioxadiazine-furazan system: structural modification by incorporating versatile functionalities

2017 ◽  
Vol 46 (41) ◽  
pp. 14301-14309 ◽  
Author(s):  
Qiong Yu ◽  
Guangbin Cheng ◽  
Xuehai Ju ◽  
Chunxu Lu ◽  
Qiuhan Lin ◽  
...  
Keyword(s):  
Structural Modification ◽  
Layer Structure ◽  
Layer By Layer ◽  
Thermal Stabilities

An N-trinitroethylamino derivative and amminonium salt based on the 1,4,2,5-dioxadiazene-furazan system are synthesized and characterized. Due to their layer-by-layer structure, these two compounds show good thermal stabilities and low sensitivities.

scholarly journals A Solvent-Mediated Excited-State Intermolecular Proton Transfer Fluorescent Probe for Fe3+ Sensing and Cell Imaging

Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 516
Author(s):  
You Qian ◽  
Fuchun Gong ◽  
Jiguang Li ◽  
Pan Ma ◽  
Hanming Zhu ◽  
...  
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Fluorescent Probe ◽  
Cell Imaging ◽  
Cyano Group ◽  
Proton Donor ◽  
Cell Permeability ◽  
One Pot ◽  
Intermolecular Proton Transfer ◽  
Synthesis Strategy

Constructing excited-state intermolecular proton transfer (ESIPT-e) fluorophores represents significant challenges due to the harsh requirement of bearing a proton donor-acceptor (D-A) system and their matching proton donating-accepting ability in the same molecule. Herein, we synthesized a new-type ESIPT-e fluorophor (2-APC) using the “four-component one-pot” reaction. By the installing of a cyano-group on pyridine scaffold, the proton donating ability of -NH2 was greatly enhanced, enabling 2-APC to undergo ESIPT-e process. Surprisingly, 2-APC exhibited dual-emissions in protic solvents ethanol and normal fluorescence in aprotic solvents, which is vastly different from that of conventional ESIPT-a dyes. The ESIPT emission can be obviously suppressed by Fe3+ due to the coordination reaction of Fe3+ with the A-D system in 2-APC. From this basis, a highly sensitive and selective method was established using 2-APC as a fluorescent probe, which offers the sensitive detection of Fe3+ ranging from 0 to 13 μM with the detection limit of 7.5 nM. The recovery study of spiked Fe3+ measured by the probe showed satisfactory results (97.2103.4%) with the reasonable RSD ranging from 3.1 to 3.8%. Moreover, 2-APC can also exhibit aggregation-induced effect in poor solvent or solid-state, eliciting strong red fluorescence. 2-APC was also applied to cell-imaging, exhibiting good cell-permeability, biocompatibility and color rendering. This multi-mode emission of 2-APC is significant departure from that of conventional extended p-conjugated systems and ESIPT dyes based on a flat and rigid molecular design. The “one-pot synthesis” strategy for the construction of ESIPT molecules pioneered a new route to achieve tricolor-emissive fluorophores.

scholarly journals SPECIFIC NATURE OF ACID-BASE INTERACTION OF OCTA(4-TERT-BUTYLPHENYL)TETRAPYRAZINOPORPHYRAZINE WITH ORGANIC PROTON-ACCEPTOR MOLECULES IN BENZENE

2021 ◽  
Vol 64 (3) ◽  
pp. 33-40
Author(s):  
Oleg A. Petrov ◽  
Aleksandr S. Semeykin ◽  
Mariya V. Shilovskaya ◽  
Tatiana V. Lyubimova
Keyword(s):  
Proton Transfer ◽  
Proton Acceptor ◽  
Base System ◽  
Excess Charge ◽  
Hydrogen Atoms ◽  
Acid Base ◽  
Base Interaction ◽  
Base Equilibrium ◽  
Acid Base Equilibrium ◽  
Acid Base Interaction

The reaction of acid-base interaction of octa(4-tert-butylphenyl)tetrapyrazinophosphyrazine with pyridine, 2-methylpyridine, morhpoline, pipyridine, n-butylamine, tert-butylamine, diethylamine, triethylamine and dimethylsulfoxide in benzene was investigated. It is shown that the researched porphyrazine forms kinetically stable proton transfer complexes with pyridine, 2-methylpyridine, morpholine and dimethylsulfoxide. In benzene-base system an acid-base equilibrium between the molecular form of octa(4-tert-butylphenyl)tetrapyrazinoporphyrazine and its proton transfer complex was established. The interaction of substituted tetrapyrazinoporphyrazine with morpholine in benzene was revealed to be a kinetically controllable process which occurs with low reaction rate and high values of activation energy. Such values are not inherent to most of relatively simple liquid-phase acid-base systems. The kinetic equation of the process was found, and, based on the spectral changes accompanying the reaction, a cheme of two-stage process of proton transfer of NH-groups of octa(4-tert-butylphenyl)tetrapyrazinoporphyrazine to morpholine in benzene was proposed. A possible structure of proton transfer complex of octa(4-tert-butylphenyl)tetrapyrazinoporphyrazine with organic bases is shown. In these complexes the inner hydrogen atoms of the cycle, bonded with base molecules, lie under and above the plane of the molecule, and the proton transfer from acid to base is limited either by the H-complex or the ion-ion associates constituting an H-bonded ion pair. Depending on the proton accepting tendency of the base, the acid-base equilibrium can shift towards or away from the more or less polarized structure. It was revealed that in benzene - n-butylamine (tri-butylamine, diethylamine, triethylamine, pipyridine) system the acid-base interaction involving octa(4- tert-butylphenyl)tetrapyrazinoporphyrazine occurs incredibly fast, with rates not measurable by standard spectrophotography methods. The forming proton transfer complexes are highly labile due to concurrent proton reaction occurring, leading to the formation of dianion form of octa(4- tert-butylphenyl)tetrapyrazinoporphyrazine. This form undergoes spontaneous dissolution into low-molecular colorless products due to the lack of compensation of excess charge in the macrocycle.

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