scholarly journals Rigidly hydrogen-bonded water molecules facilitate proton transfer in photosystem II

2020 ◽  
Vol 22 (28) ◽  
pp. 15831-15841
Author(s):  
Naoki Sakashita ◽  
Hiroshi Ishikita ◽  
Keisuke Saito
Keyword(s):  
Photosystem Ii ◽  
Proton Transfer ◽  
Water Molecules ◽  
Hydrogen Bonded

In the channel of photosystem II, rigidly hydrogen-bonded water molecules facilitate the Grotthuss-like proton transfer, whereas flexible water molecules prevent proton transfer in the channel of aquaporin.

scholarly journals Molecular Recognition in Proton-Transfer Compounds of Brucine with Achiral Substituted Salicylic Acid Analogues

2006 ◽  
Vol 59 (5) ◽  
pp. 320 ◽  
Author(s):  
Graham Smith ◽  
Urs D. Wermuth ◽  
Peter C. Healy ◽  
Jonathan M. White
Keyword(s):  
Proton Transfer ◽  
Three Dimensional ◽  
Water Molecules ◽  
Sulfosalicylic Acid ◽  
X Ray ◽  
X Ray Crystallography ◽  
Guest Species ◽  
Substituted Benzoic Acids ◽  
Proton Transfer Compounds ◽  
Hydrogen Bonded

The 1:1 proton-transfer brucinium compounds from the reaction of the alkaloid brucine with 5-nitrosalicylic acid, 3,5-dinitrosalicylic acid, and 5-sulfosalicylic acid, namely anhydrous brucinium 5-nitrosalicylate (1), brucinium 3,5-dinitrosalicylate monohydrate (2), and brucinium 5-sulfosalicylate trihydrate (3) have been prepared and their crystal structures determined by X-ray crystallography. All structures further demonstrate the selectivity of brucine for meta-substituted benzoic acids and comprise three-dimensional hydrogen-bonded framework polymers. Two of the compounds (1 and 3) have the previously described undulating brucine sheet host-substructures which incorporate interstitially hydrogen-bonded salicylate anion guest species and additionally in 3 the water molecules of solvation. The structure of 2 differs in having a three-centre brucinium–salicylate anion bidentate N+–H···O(carboxyl) hydrogen-bonding association linking the species through interstitial associations involving also the water molecules of solvation. A review of the crystallographic structural literature on strychnine and brucine is also given.

Bis{4-[(4-pyridyl)ethenyl]pyridinium} 4-sulfonatobenzoate trihydrate

2006 ◽  
Vol 62 (4) ◽  
pp. o1529-o1531 ◽  
Author(s):  
Li-Ping Zhang ◽  
Long-Guan Zhu
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Proton Transfer ◽  
Water Molecules ◽  
Stacking Interactions ◽  
Two Dimensional ◽  
One Dimensional ◽  
Π Stacking ◽  
Dimensional Network ◽  
Hydrogen Bonded

In the crystal structure of the title organic proton-transfer complex, 2C12H11N2 +·C7H4O5S2−·3H2O, the cations form one-dimensional chains via intermolecular N—H...N hydrogen bonds and these chains, in turn, form a two-dimensional network through π–π stacking interactions. In addition, the anions and water molecules are connected into a two-dimensional hydrogen-bonded network through intermolecular O—H...O hydrogen bonds. The two motifs result in sheets of cations and anions stacked alternately.

scholarly journals Energetics of the Proton Transfer Pathway for Tyrosine D in Photosystem II

2016 ◽  
Vol 69 (9) ◽  
pp. 991 ◽  
Author(s):  
Keisuke Saito ◽  
Naoki Sakashita ◽  
Hiroshi Ishikita
Keyword(s):  
Hydrogen Bond ◽  
Photosystem Ii ◽  
Proton Transfer ◽  
Electrostatic Interactions ◽  
Water Molecules ◽  
Hydrogen Bond Network ◽  
Redox States ◽  
Redox Active ◽  
Bond Network ◽  
Tyrosine D

The proton transfer pathway for redox active tyrosine D (TyrD) in photosystem II is a hydrogen-bond network that involves D2-Arg180 and a series of water molecules. Using quantum mechanical/molecular mechanical calculations, the detailed properties of the energetics and structural geometries were investigated. The potential-energy profile of all hydrogen bonds along the proton transfer pathway indicates that the overall proton transfer from TyrD is energetically downhill. D2-Arg180 plays a key role in the proton transfer pathway, providing a driving force for proton transfer, maintaining the hydrogen-bond network structure, stabilising P680•+, and thus deprotonating TyrD-OH to TyrD-O•. A hydrophobic environment near TyrD enhances the electrostatic interactions between TyrD and redox active groups, e.g. P680 and the catalytic Mn4CaO5 cluster: the redox states of those groups are linked with the protonation state of TyrD, i.e. release of the proton from TyrD. Thus, the proton transfer pathway from TyrD may ultimately contribute to the conversion of S0 into S1 in the dark in order to stabilise the Mn4CaO5 cluster when the photocycle is interrupted in S0.

scholarly journals Three-dimensional hydrogen-bonded structures in the hydrated proton-transfer salts of isonipecotamide with the dicarboxylic oxalic and adipic acid homologues

2013 ◽  
Vol 69 (10) ◽  
pp. 1192-1195
Author(s):  
Graham Smith ◽  
Urs D. Wermuth
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Proton Transfer ◽  
Adipic Acid ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Water Molecules ◽  
Solvent Water ◽  
Hydrated Proton ◽  
Hydrogen Bonded

The structures of the 1:1 hydrated proton-transfer compounds of isonipecotamide (piperidine-4-carboxamide) with oxalic acid, 4-carbamoylpiperidinium hydrogen oxalate dihydrate, C6H13N2O+·C2HO4−·2H2O, (I), and with adipic acid, bis(4-carbamoylpiperidinium) adipate dihydrate, 2C6H13N2O+·C6H8O42−·2H2O, (II), are three-dimensional hydrogen-bonded constructs involving several different types of enlarged water-bridged cyclic associations. In the structure of (I), the oxalate monoanions give head-to-tail carboxylic acid O—H...Ocarboxylhydrogen-bonding interactions, formingC(5) chain substructures which extend alonga. The isonipecotamide cations also give parallel chain substructures through amide N—H...O hydrogen bonds, the chains being linked acrossband downcby alternating water bridges involving both carboxyl and amide O-atom acceptors and amide and piperidinium N—H...Ocarboxylhydrogen bonds, generating cyclicR43(10) andR32(11) motifs. In the structure of (II), the asymmetric unit comprises a piperidinium cation, half an adipate dianion, which lies across a crystallographic inversion centre, and a solvent water molecule. In the crystal structure, the two inversion-related cations are interlinked through the two water molecules, which act as acceptors in dual amide N—H...Owaterhydrogen bonds, to give a cyclicR42(8) association which is conjoined with anR44(12) motif. Further N—H...Owater, water O—H...Oamideand piperidinium N—H...Ocarboxylhydrogen bonds give the overall three-dimensional structure. The structures reported here further demonstrate the utility of the isonipecotamide cation as a synthon for the generation of stable hydrogen-bonded structures. The presence of solvent water molecules in these structures is largely responsible for the non-occurrence of the common hydrogen-bonded amide–amide dimer, promoting instead various expanded cyclic hydrogen-bonding motifs.

scholarly journals Cyclooctanaminium hydrogen succinate monohydrate

2012 ◽  
Vol 68 (4) ◽  
pp. o1204-o1204 ◽  
Author(s):  
Sanaz Khorasani ◽  
Manuel A. Fernandes
Keyword(s):  
Hydrogen Bonds ◽  
Water Molecule ◽  
Ammonium Cation ◽  
Water Molecules ◽  
Hydrated Salt ◽  
A Chain ◽  
Hydrogen Bonded

In the title hydrated salt, C8H18N+·C4H5O4−·H2O, the cyclooctyl ring of the cation is disordered over two positions in a 0.833 (3):0.167 (3) ratio. The structure contains various O—H.·O and N—H...O interactions, forming a hydrogen-bonded layer of molecules perpendicular to thecaxis. In each layer, the ammonium cation hydrogen bonds to two hydrogen succinate anions and one water molecule. Each hydrogen succinate anion hydrogen bonds to neighbouring anions, forming a chain of molecules along thebaxis. In addition, each hydrogen succinate anion hydrogen bonds to two water molecules and the ammonium cation.

Damaging Intermolecular Energy and Proton Transfer Processes in Alpha-Particle-Irradiated Hydrogen-Bonded Systems

2018 ◽  
Vol 130 (52) ◽  
pp. 17269-17273 ◽  
Author(s):  
Shenyue Xu ◽  
Dalong Guo ◽  
Xinwen Ma ◽  
Xiaolong Zhu ◽  
Wentian Feng ◽  
...  
Keyword(s):  
Proton Transfer ◽  
Alpha Particle ◽  
Transfer Processes ◽  
Intermolecular Energy ◽  
Hydrogen Bonded Systems ◽  
Hydrogen Bonded

Excited-State Intramolecular Proton Transfer in Polymers

1995 ◽  
Vol 413 ◽  
Author(s):  
Richard M. Tarkka ◽  
Samson A. Jenekhe
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Main Chain ◽  
Intramolecular Proton Transfer ◽  
Polymer Structure ◽  
Laser Dyes ◽  
Excimer Formation ◽  
Photochromic Materials ◽  
Hydrogen Bonded

ABSTRACTExcited state intramolecular proton transfer (ESIPT) has been demonstrated in new intramoleculary hydrogen bonded (IHB) polymers of interest as photostabilizers, triplet quenchers, photochromic materials, laser dyes and electroluminescent materials. The new IHB polymers containing the 2-(2-hydroxyphenyl)benzoxazole moiety in the main chain were used to explore the effects of polymer structure, extended conjugation and competition with excimer formation on the ESIPT process. It was found that polymer structure, and particularly extent of conjugation, affects an IHB polymer's ability to exhibit ESIPT.

Syntheses and crystal structures of two magnesium–tetrazole compounds in salt and polymeric forms

2015 ◽  
Vol 71 (3) ◽  
pp. 222-228 ◽  
Author(s):  
Mohamed Abdellatif Bensegueni ◽  
Aouatef Cherouana ◽  
Slimane Dahaoui
Keyword(s):  
Alkaline Earth ◽  
Three Dimensional ◽  
Polymer Chains ◽  
Magnesium Ion ◽  
Water Molecules ◽  
Compound I ◽  
Hydrothermal Conditions ◽  
One Dimensional ◽  
Polymeric Chains ◽  
Hydrogen Bonded

Two alkaline earth–tetrazole compounds, namelycatena-poly[[[triaquamagnesium(II)]-μ-5,5′-(azanediyl)ditetrazolato-κ3N1,N1′:N5] hemi{bis[μ-5,5′-(azanediyl)ditetrazolato-κ3N1,N1′:N2]bis[triaquamagnesium(II)]} monohydrate], {[Mg(C2HN9)(H2O)3][Mg2(C2HN9)2(H2O)6]0.5·H2O}n, (I), and bis[5-(pyrazin-2-yl)tetrazolate] hexaaquamagnesium(II), (C5H3N6)[Mg(H2O)6], (II), have been prepared under hydrothermal conditions. Compound (I) is a mixed dimer–polymer based on magnesium ion centres and can be regarded as the first example of a magnesium–tetrazolate polymer in the crystalline form. The structure shows a complex three-dimensional hydrogen-bonded network that involves magnesium–tetrazolate dimers, solvent water molecules and one-dimensional magnesium–tetrazolate polymeric chains. The intrinsic cohesion in the polymer chains is ensured by N—H...N hydrogen bonds, which formR22(7) rings, thus reinforcing the propagation of the polymer chain along theaaxis. The crystal structure of magnesium tetrazole salt (II) reveals a mixed ribbon of hydrogen-bonded rings, of typesR22(7),R22(9) andR24(10), running along thecaxis, which are linked byR24(16) rings, generating a 4,8-cflunet.

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