scholarly journals Chirality Transfer in a Calixarene-Based Directional Pseudorotaxane Complex

Chemistry ◽  
2021 ◽  
Vol 3 (3) ◽  
pp. 1089-1100
Author(s):  
Gerardo Concilio ◽  
Carmine Gaeta ◽  
Paolo Della Della Sala ◽  
Veronica Iuliano ◽  
Carmen Talotta ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Optical Rotation ◽  
Aromatic Rings ◽  
Chirality Transfer ◽  
Methyl Group ◽  
Π Interactions

Hexamethoxycalix[6]arene 3 forms a directional pseudorotaxane complex with the chiral axle (S)-(α-methyl-benzyl)benzylammonium 2+. Between the two (endo-chiral)-2+@3 and (exo-chiral)-2+@3 pseudorotaxane stereoisomers, the former is preferentially formed. This result confirms the validity of the “endo-α-methyl-benzyl rule”, previously reported by us. DFT calculations suggest that C-H···π interactions between the methyl group of 2+ and the calixarene aromatic rings, determine the stereoselectivity of the threading process toward the “endo-α-methyl-benzyl preference”. An amplification of optical rotation is observed upon formation of the pseudorotaxane complex (endo-chiral)-2+@3 with respect to free axle 2+. Thus, the specifical rotation of the 1:1 mixture of chiral 2+∙B(ArF)4− salt and achiral 3 was augmented upon formation of the pseudorotaxane and DFT calculations were used to rationalize this result.

Reactions of an Aluminium(I) Reagent with 1,2-, 1,3- and 1,5-Dienes: Dearomatisation, Reversibility, and a Pericyclic Mechanism

2019 ◽  
Author(s):  
Clare Bakewell ◽  
Martí Garçon ◽  
Richard Y Kong ◽  
Louisa O'Hare ◽  
Andrew J. P. White ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Dft Calculations ◽  
Transition State ◽  
Reaction Pathways ◽  
Aromatic Rings ◽  
Aromatic Character ◽  
Pericyclic Reaction

The reactions of an aluminium(I) reagent with a series of 1,2-, 1,3- and 1,5-dienes are reported. In the case of 1,3-dienes the reaction occurs by a pericyclic reaction mechanism, specifically a cheletropic cycloaddition, to form aluminocyclopentene containing products. This mechanism has been interrogated by stereochemical experiments and DFT calculations. The stereochemical experiments show that the (4+1) cycloaddition follows a suprafacial topology, while calculations support a concerted albeit asynchronous pathway in which the transition state demonstrates aromatic character. Remarkably, the substrate scope of the (4+1) cycloaddition includes dienes that are either in part, or entirely, contained within aromatic rings. In these cases, reactions occur with dearomatisation of the substrate and can be reversible. In the case of 1,2- or 1,5-dienes complementary reactivity is observed; the orthogonal nature of the C=C π-bonds (1,2-diene) and the homoconjugated system (1,5-diene) both disfavour a (4+1) cycloaddition. Rather, reaction pathways are determined by an initial (2+1) cycloaddition to form an aluminocyclopropane intermediate which can in turn undergo insertion of a further C=C π-bond leading to complex organometallic products that incorporate fused hydrocarbon rings.

scholarly journals N′-(3-Hydroxybenzylidene)-4-methylbenzohydrazide

2012 ◽  
Vol 68 (6) ◽  
pp. o1816-o1816
Author(s):  
Ji-Lai Liu ◽  
Ming-Hui Sun ◽  
Jing-Jun Ma
Keyword(s):  
Hydrogen Bonds ◽  
Dihedral Angle ◽  
Title Compound ◽  
Crystal Packing ◽  
Aromatic Rings ◽  
Π Interactions ◽  
Compound C ◽  
Centroid Distance ◽  
Benzene Rings

The title compound, C15H14N2O2, was obtained from the reaction of 3-hydroxybenzaldhyde and 4-methylbenzohydrazide in methanol. In the molecule, the benzene rings form a dihedral angle of 2.9 (3)°. In the crystal, N—H...O and O—H...O hydrogen bonds link the molecules into layers parallel to (101). The crystal packing also exhibits π–π interactions between the aromatic rings [centroid–centroid distance = 3.686 (4) Å].

Dual role of silver in a fluorogenic N-squaraine probe based on Ag(I)-π interactions

2021 ◽  
Author(s):  
Manel Vega ◽  
Salvador Blasco ◽  
Enrique García-España ◽  
Bartolome Soberats ◽  
Antonio Frontera ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Experimental Evidence ◽  
Dual Role ◽  
Π Interactions ◽  
Turn On

In the presence of Ag(I), the monoanion of a cyano-N-squaraine (I) generates an intense fluorescent turn-on response. Experimental evidence and DFT calculations reveal a sequence of deprotonation-coordination events in which...

scholarly journals Crystal structures of 2-methylpyridinium hydrogen 2,3-bis(4-methylbenzoyloxy)succinate and bis-[4-methylpyridinium hydrogen 2,3-bis(4-methylbenzoyloxy)succinate] pentahydrate

2017 ◽  
Vol 73 (10) ◽  
pp. 1483-1487
Author(s):  
P. Sivakumar ◽  
S. Israel ◽  
G. Chakkaravarthi
Keyword(s):  
Hydrogen Bonds ◽  
Pyridine Ring ◽  
Crystal Packing ◽  
Water Molecules ◽  
Two Dimensional ◽  
Asymmetric Unit ◽  
Aromatic Rings ◽  
Π Interactions ◽  
Dimensional Network ◽  
Anions And Cations

The title salt (I), C6H8N+·C20H17O8−, comprises a 2-methylpyridinium cation and a 2,3-bis(4-methylbenzoyloxy)succinate mono-anion while the salt (II), 2C6H8N+·2C20H17O8−·5H2O, consists of a pair of 4-methylpyridinium cations and 2,3-bis(4-methylbenzoyloxy)succinate mono-anions and five water molecules of solvation in the asymmetric unit. In (I), the dihedral angle between the aromatic rings of the anion is 40.41 (15)°, comparing with 43.0 (3) and 85.7 (2)° in the conformationally dissimilar anion molecules in (II). The pyridine ring of the cation in (I) is inclined at 23.64 (16) and 42.69 (17)° to the two benzene moieties of the anion. In (II), these comparative values are 4.7 (3), 43.5 (3)° and 43.5 (3), 73.1 (3)° for the two associated cation and anion pairs. The crystal packing of (I) is stabilized by inter-ionic N—H...O, O—H...O and C—H...O hydrogen bonds as well as weak C—H...π interactions, linking the ions into infinite chains along [100]. In the crystal packing of (II), the anions and cations are also linked by N—H...O and O—H...O hydrogen bonds involving also the water molecules, giving a two-dimensional network across (001). The crystal structure is also stabilized by weak C—H...O and C—H...π interactions.

scholarly journals (E)-2-Methyl-6-{[(5-methylpyridin-2-yl)imino]methyl}phenol

IUCrData ◽  
2017 ◽  
Vol 2 (1) ◽  
Author(s):  
Md. Azharul Arafath ◽  
Farook Adam ◽  
Mohd. R. Razali
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Dihedral Angle ◽  
Title Compound ◽  
Zigzag Chain ◽  
Aromatic Rings ◽  
Methyl Group ◽  
Compound C

In the title compound, C14H14N2O, the dihedral angle between the aromatic rings is 5.54 (9)°. The conformation is reinforced by an intramolecular O—H...N hydrogen bond, which closes anS(6) ring. The pyridine N atom and methyl group lie to opposite sides of the molecule. In the crystal, the molecules are linked into a zigzag chain propagating in [0-11] by weak C—H...O hydrogen bonds.

Exploration of relative π-electron localization in naphthalene aromatic rings by C–H⋯π interactions: experimental evidence, computational criteria, and database analysis

CrystEngComm ◽  
2019 ◽  
Vol 21 (42) ◽  
pp. 6432-6445 ◽  
Author(s):  
Ali Samie ◽  
Alireza Salimi ◽  
Jered C. Garrison
Keyword(s):  
Experimental Evidence ◽  
Aromatic Ring ◽  
Electron Localization ◽  
Aromatic Rings ◽  
Database Analysis ◽  
Π Interactions ◽  
Contact Position

In C–H⋯π interaction, the relative π-electron localization in aromatic ring led to the change of contact position from centre to edges of the ring (C–H⋯πe) which was confirmed by experimental evidences, computational criteria, and database analysis.

Pd−N−H···Cl−Pd Hydrogen Bonds and π−π Interactions between Fluorinated Aromatic Rings intrans-[PdCl2(NH2ArF)2]

2007 ◽  
Vol 7 (1) ◽  
pp. 117-123 ◽  
Author(s):  
Oscar Baldovino-Pantaleón ◽  
David Morales-Morales ◽  
Simón Hernández-Ortega ◽  
Rubén A. Toscano ◽  
Jesús Valdés-Martínez
Keyword(s):  
Hydrogen Bonds ◽  
Aromatic Rings ◽  
Π Interactions

scholarly journals 2-Bromo-1-(1-phenylsulfonyl-1H-indol-3-yl)propan-1-one

2014 ◽  
Vol 70 (3) ◽  
pp. o295-o296
Author(s):  
C. Ramathilagam ◽  
P. R. Umarani ◽  
V. Saravanan ◽  
A. K. Mohanakrishnan ◽  
B. Gunasekaran ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Dihedral Angle ◽  
Title Compound ◽  
Phenyl Ring ◽  
Ring System ◽  
Indole Ring ◽  
Methyl Group ◽  
Π Interactions ◽  
Compound C ◽  
A Chain

In the title compound, C17H14BrNO3S, the phenyl ring makes a dihedral angle of 89.78 (16)° with the plane of the indole ring system. The terminal Br atom and the methyl group are disordered over two sets of sites, with site occupancies of 0.860 (2) and 0.140 (2). In the crystal, molecules are linked into a chain along theb-axis direction by weak C—H...O hydrogen bonds. The chains are further linked by C—H...π interactions, forming layers parallel to thebcplane.

scholarly journals 2-[(1-Methyl-1H-pyrrol-2-yl)methylidene]propanedinitrile

2012 ◽  
Vol 68 (4) ◽  
pp. o1170-o1170
Author(s):  
Abdullah M. Asiri ◽  
Hassan M. Faidallah ◽  
Shaeel A. Al-Thabaiti ◽  
Seik Weng Ng ◽  
Edward R. T. Tiekink
Keyword(s):  
Title Compound ◽  
Crystal Packing ◽  
Methyl Group ◽  
Π Interactions ◽  
Compound C ◽  
Centroid Distance ◽  
Ring Centroid

In the title compound, C9H7N3, the N-bound methyl group and vinyl H atom aresyn. The 12 non-H atoms comprising the molecule are essentially coplanar (r.m.s. deviation = 0.071 Å). Supramolecular tapes feature in the crystal packing, orientated perpendicular to [10-1], and are formed by C—H...N interactions involving each cyano N atom. The tapes are connected into layersviaπ–π interactions occurring between translationally related pyrrole rings [ring centroid–centroid distance = 3.8754 (10) Å]; the layers stack along thebaxis.

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