scholarly journals Binding Between Cyclohexanohemicucurbit[n]urils and Polar Organic Guests

2021 ◽  
Vol 9 ◽  
Author(s):  
Lukas Ustrnul ◽  
Tatsiana Burankova ◽  
Mario Öeren ◽  
Kristina Juhhimenko ◽  
Jenni Ilmarinen ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Atomic Charge ◽  
Hydrogen Bond Donor ◽  
H Nmr ◽  
Partial Charges ◽  
Potential Applications ◽  
Halogenated Solvents ◽  
Organic Guests ◽  
Nmr Titrations ◽  
Formation Of Complexes

Inherently chiral, barrel-shaped, macrocyclic hosts such as cyclohexanohemicucurbit[n]urils (cycHC[n]) bind zinc porphyrins and trifluoroacetic acid externally in halogenated solvents. In the current study, we tested a set of eighteen organic guests with various functional groups and polarity, namely, thiophenols, phenols, and carboxylic and sulfonic acids, to identify a preference toward hydrogen bond–donating molecules for homologous cycHC[6] and cycHC[8]. Guests were characterized by Hirshfeld partial charges on acidic hydrogens and their binding by 1H and 19F NMR titrations. Evaluation of association constants revealed the complexity of the system and indirectly proved an external binding with stoichiometry over 2:1 for both homologs. It was found that overall binding strength is influenced by the stoichiometry of the formed complexes, the partial atomic charge on the hydrogen atom of the hydrogen bond donor, and the bulkiness of the guest. Additionally, a study on the formation of complexes with halogen anions (Cl− and Br−) in methanol and chloroform, analyzed by 1H NMR, did not confirm complexation. The current study widens the scope of potential applications for host molecules by demonstrating the formation of hydrogen-bonded complexes with multisite hydrogen bond acceptors such as cycHC[6] and cycHC[8].

scholarly journals Stereochemical outcomes of C–F activation reactions of benzyl fluoride

2018 ◽  
Vol 14 ◽  
pp. 106-113 ◽  
Author(s):  
Neil S Keddie ◽  
Pier Alexandre Champagne ◽  
Justine Desroches ◽  
Jean-François Paquin ◽  
David O'Hagan
Keyword(s):  
Hydrogen Bond ◽  
Liquid Crystal ◽  
Halogen Bonds ◽  
Hydrogen Bond Donor ◽  
Nucleophilic Substitutions ◽  
Reaction Conditions ◽  
Activation Reaction ◽  
H Nmr ◽  
Nmr Method ◽  
Chiral Liquid Crystal

In recent years, the highly polar C–F bond has been utilised in activation chemistry despite its low reactivity to traditional nucleophiles, when compared to other C–X halogen bonds. Paquin’s group has reported extensive studies on the C–F activation of benzylic fluorides for nucleophilic substitutions and Friedel–Crafts reactions, using a range of hydrogen bond donors such as water, triols or hexafluoroisopropanol (HFIP) as the activators. This study examines the stereointegrity of the C–F activation reaction through the use of an enantiopure isotopomer of benzyl fluoride to identify whether the reaction conditions favour a dissociative (SN1) or associative (SN2) pathway. [2H]-Isotopomer ratios in the reactions were assayed using the Courtieu 2H NMR method in a chiral liquid crystal (poly-γ-benzyl-L-glutamate) matrix and demonstrated that both associative and dissociative pathways operate to varying degrees, according to the nature of the nucleophile and the hydrogen bond donor.

Aliphatic Carboxylic Acid as Hydrogen-Bond Donor for Converting CO2 and Epoxide into Cyclic Carbonate under Mild Conditions

2021 ◽  
Author(s):  
Zheng Wang ◽  
Yajun Wang ◽  
Qianjie Xie ◽  
Zhiying Fan ◽  
Yehua Shen
Keyword(s):  
Hydrogen Bond ◽  
Carboxylic Acid ◽  
Value Added ◽  
Cyclic Carbonate ◽  
Hydrogen Bond Donor ◽  
Title Reaction ◽  
Aliphatic Carboxylic Acid ◽  
Mild Conditions ◽  
Atmospheric Carbon

The coupling of CO2 and epoxide is promising way to reduce atmospheric carbon by converting it into value-added cyclic carbonate. Pursuing efficient catalysts is highly attractive for the title reaction....

Role of the hydrogen bond donor component for a proper development of novel hydrophobic deep eutectic solvents

2019 ◽  
Vol 281 ◽  
pp. 423-430 ◽  
Author(s):  
Matteo Tiecco ◽  
Federico Cappellini ◽  
Francesco Nicoletti ◽  
Tiziana Del Giacco ◽  
Raimondo Germani ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Deep Eutectic Solvents ◽  
Hydrogen Bond Donor

Identifying Selective Host–Guest Interactions Based on Hydrogen Bond Donor–Acceptor Pattern in Functionalized Al-MIL-53 Metal–Organic Frameworks

2013 ◽  
Vol 117 (39) ◽  
pp. 19991-20001 ◽  
Author(s):  
Julia Wack ◽  
Renée Siegel ◽  
Tim Ahnfeldt ◽  
Norbert Stock ◽  
Luís Mafra ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Metal Organic Frameworks ◽  
Hydrogen Bond Donor ◽  
Donor Acceptor ◽  
Metal Organic

Configurational and conformational studies on condensation products of biogenic amines with 2,5-anhydro-D-mannose

1985 ◽  
Vol 63 (11) ◽  
pp. 2915-2921 ◽  
Author(s):  
Ian M. Piper ◽  
David B. MacLean ◽  
Romolo Faggiani ◽  
Colin J. L. Lock ◽  
Walter A. Szarek
Keyword(s):  
Hydrogen Bond ◽  
Intermolecular Hydrogen Bond ◽  
Direct Methods ◽  
Conformational Studies ◽  
X Ray ◽  
X Ray Crystallography ◽  
H Nmr ◽  
Twist Conformation ◽  
Cell Dimensions ◽  
Internal Hydrogen Bond

The products of a Pictet–Spengler condensation of tryptamine and of histamine with 2,5-anhydro-D-mannose have been studied by X-ray crystallography to establish their absolute configuration. 1(S)-(α-D-Arabinofuranosyl)-1,2,3,4-tetrahydro-β-carboline (1), C16H20N20O4, is monoclinic, P21 (No. 4), with cell dimensions a = 13.091(4), b = 5.365(1), c = 11.323(3) Å, β = 115.78(2)°, and Z = 2. 4-(α-D-Arabinofuranosyl)imidazo[4,5-c]-4,5,6,7-tetrahydropyridine (3), C11H17N3O4, is orthorhombic, P212121 (No. 19), with cell dimensions a = 8.118(2), b = 13.715(4), c = 10.963(3) Å, and Z = 4. The structures were determined by direct methods and refined to R1 = 0.0514, R2 = 0.0642 for 3210 reflections in the case of 1, and to R1 = 0.0312, R2 = 0.0335 for 1569 reflections in the case of 3. Bond lengths and angles within both molecules are normal and agree well with those observed in related structures. In 3 the base and sugar adopt a syn arrangement, which is maintained by an internal hydrogen bond between O(2′) and N(3). The sugar adopts a normal 2T3 twist conformation. The sugar has the opposite anti arrangement in the β-carboline 1 and the conformation of the sugar is unusual; it is close to an envelope conformation with O(4′) being the atom out of the plane. This conformation is caused by a strong intermolecular hydrogen bond from O(5′) in a symmetry-related molecule to O(4′). Both compounds are held together in the crystal by extensive hydrogen-bonding networks. The conformations of the compounds in solution have been investigated by 1H nmr spectroscopy, and the results obtained were compared with those obtained by X-ray crystallography for 1 and 3.

6,9-Dibromo-2a,10b-diphenyl-2a,5,10,10b-tetrahydro-2H,3H-2,3,4a,10a-tetraazabenzo[g]cyclopenta[cd]azulene-1,4-dione monohydrate

2006 ◽  
Vol 62 (5) ◽  
pp. o1754-o1755
Author(s):  
Neng-Fang She ◽  
Sheng-Li Hu ◽  
Hui-Zhen Guo ◽  
An-Xin Wu
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Water Molecule ◽  
Title Compound ◽  
Supramolecular Structure ◽  
Hydrogen Bond Donor ◽  
Hydrogen Bond Acceptor ◽  
Compound C ◽  
Bifurcated Hydrogen Bond

The title compound, C24H18Br2N4O2·H2O, forms a supramolecular structure via N—H...O, O—H...O and C—H...O hydrogen bonds. In the crystal structure, the water molecule serves as a bifurcated hydrogen-bond acceptor and as a hydrogen-bond donor.

scholarly journals Facile and Promising Method for Michael Addition of Indole and Pyrrole to Electron-Deficienttrans-β-Nitroolefins Catalyzed by a Hydrogen Bond Donor Catalyst Feist’s Acid and Preliminary Study of Antimicrobial Activity

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Abdullah M. A. Al Majid ◽  
Mohammad Shahidul Islam ◽  
Assem Barakat ◽  
Mohamed H. M. Al-Agamy ◽  
Mu. Naushad
Keyword(s):  
Antimicrobial Activity ◽  
Hydrogen Bond ◽  
Michael Addition ◽  
Hydrogen Bond Donor ◽  
New Class ◽  
Optimum Reaction ◽  
Preliminary Study ◽  
Cooperative Hydrogen Bonding ◽  
The Michael Addition

The importance of cooperative hydrogen-bonding effects has been demonstrated using novel 3-methylenecyclopropane-1,2-dicarboxylic acid (Feist’s acid (FA)) as hydrogen bond donor catalysts for the addition of indole and pyrrole totrans-β-nitrostyrene derivatives. Because of the hydrogen bond donor (HBD) ability, Feist’s acid (FA) has been introduced as a new class of hydrogen bond donor catalysts for the activation of nitroolefin towards nucleophilic substitution reaction. It has effectively catalyzed the Michael addition of indoles and pyrrole toβ-nitroolefins under optimum reaction condition to furnish the corresponding Michael adducts in good to excellent yields (up to 98%). The method is general, atom-economical, convenient, and eco-friendly and could provide excellent yields and regioselectivities. Some newly synthesized compounds were for examinedin vitroantimicrobial activity and their preliminary results are reported.

Hydrogen bond donor functionalized poly(ionic liquid)s for efficient synergistic conversion of CO2 to cyclic carbonates

2020 ◽  
Author(s):  
Haibin Gou ◽  
Xifei Ma ◽  
Qian Su ◽  
Lei Liu ◽  
Ting Ying ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Ionic Liquid ◽  
Value Added ◽  
Pivotal Role ◽  
Cyclic Carbonates ◽  
Hydrogen Bond Donor ◽  
Metal Free ◽  
Recyclable Catalysts ◽  
Poly Ionic Liquid ◽  
Value Added Products

The development of metal-free, high effective and recyclable catalysts plays a pivotal role in transforming CO2 into high value-added products such as cyclic carbonates. In this paper, we have introduced...

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