Tweezer-type binding cavity formed by the helical folding of a carbazole–pyridine oligomer

2022 ◽  
Author(s):  
Hye Jin Jang ◽  
Seungwon Lee ◽  
Byung Jun An ◽  
Geunmoo Song ◽  
Hae-Geun Jeon ◽  
...  
Keyword(s):  
Dipole Interactions ◽  
Π Stacking ◽  
Binding Cavity ◽  
Helical Folding

We have synthesised a new aromatic foldamer based on the carbazole–pyridine oligomers that adopt helical conformations via dipole-dipole interactions and π-stacking between two ethynyl bond-linked monomers. This foldamer scaffold has...

Tuning the Magnetic Vortex State in Magnetite Nanodiscs for Remote Control of Biological Signalling

2019 ◽  
Author(s):  
Danijela Gregurec ◽  
Alexander W. Senko ◽  
Andrey Chuvilin ◽  
Pooja Reddy ◽  
Ashwin Sankararaman ◽  
...  
Keyword(s):  
Remote Control ◽  
Ion Channels ◽  
Ground State ◽  
Magnetic Particles ◽  
Colloidal Stability ◽  
Vortex State ◽  
Magnetic Vortex ◽  
Electron Holography ◽  
Dipole Interactions ◽  
Magnetite Particles

In this work, we demonstrate the application of anisotropic magnetite nanodiscs (MNDs) as transducers of torque to mechanosensory cells under weak, slowly varying magnetic fields (MFs). These MNDs possess a ground state vortex configuration of magnetic spins which affords greater colloidal stability due to eliminated dipole-dipole interactions characteristic of isotropic magnetic particles of similar size. We first predict vortex magnetization using micromagnetic stimulations in sub-micron anisotropic magnetite particles and then use electron holography to experimentally investigate the magnetization of MNDs 98–226 nm in diameter. When MNDs are coupled to MFs, they transition between vortex and in-plane magnetization allowing for the exertion of the torque on the pN scale, which is sufficient to activate mechanosensitive ion channels in cell membranes.<br>

Hierarchy of π-Stacking Determines the Conformational Preference of Bis-Squaraines

2020 ◽  
Author(s):  
Abhishek Singh ◽  
Reman K. Singh ◽  
G Naresh Patwari
Keyword(s):  
Hydrogen Bonding ◽  
Rational Design ◽  
Biological Molecules ◽  
Conformational Space ◽  
X Ray Crystallography ◽  
Simple Strategy ◽  
Induced Folding ◽  
Π Stacking ◽  
Varying Length ◽  
Dynamics Simulations

The rational design of conformationally controlled foldable modules can lead to a deeper insight into the conformational space of complex biological molecules where non-covalent interactions such as hydrogen bonding and π-stacking are known to play a pivotal role. Squaramides are known to have excellent hydrogen bonding capabilities and hence, are ideal molecules for designing foldable modules that can mimic the secondary structures of bio-molecules. The π-stacking induced folding of bis-squaraines tethered using aliphatic primary and secondary-diamine linkers of varying length is explored with a simple strategy of invoking small perturbations involving the length linkers and degree of substitution. Solution phase NMR investigations in combination with molecular dynamics simulations suggest that bis-squaraines predominantly exist as extended conformations. Structures elucidated by X-ray crystallography confirmed a variety of folded and extended secondary conformations including hairpin turns and 𝛽-sheets which are determined by the hierarchy of π-stacking relative to N–H···O hydrogen bonds.

Hierarchy of π-Stacking Determines the Conformational Preference of Bis-Squaraines

2020 ◽  
Author(s):  
Abhishek Singh ◽  
Reman K. Singh ◽  
G Naresh Patwari
Keyword(s):  
Hydrogen Bonding ◽  
Rational Design ◽  
Biological Molecules ◽  
Conformational Space ◽  
X Ray Crystallography ◽  
Simple Strategy ◽  
Induced Folding ◽  
Π Stacking ◽  
Varying Length ◽  
Dynamics Simulations

The rational design of conformationally controlled foldable modules can lead to a deeper insight into the conformational space of complex biological molecules where non-covalent interactions such as hydrogen bonding and π-stacking are known to play a pivotal role. Squaramides are known to have excellent hydrogen bonding capabilities and hence, are ideal molecules for designing foldable modules that can mimic the secondary structures of bio-molecules. The π-stacking induced folding of bis-squaraines tethered using aliphatic primary and secondary-diamine linkers of varying length is explored with a simple strategy of invoking small perturbations involving the length linkers and degree of substitution. Solution phase NMR investigations in combination with molecular dynamics simulations suggest that bis-squaraines predominantly exist as extended conformations. Structures elucidated by X-ray crystallography confirmed a variety of folded and extended secondary conformations including hairpin turns and 𝛽-sheets which are determined by the hierarchy of π-stacking relative to N–H···O hydrogen bonds.

Self-Recognizing π-π Stacking Interactions Designed for the Generation of Ultrastable Mesoporous Hydrogen-Bonded Organic Frameworks

2019 ◽  
Author(s):  
KAIKAI MA ◽  
Peng Li ◽  
John Xin ◽  
Yongwei Chen ◽  
Zhijie Chen ◽  
...  
Keyword(s):  
Pore Size ◽  
Fiber Composite ◽  
Aqueous Media ◽  
Stacking Interactions ◽  
Mustard Gas ◽  
X Ray Diffraction ◽  
X Ray ◽  
Expansion Strategy ◽  
Π Stacking ◽  
Hydrogen Bonded

Creating crystalline porous materials with large pores is typically challenging due to undesired interpen-etration, staggered stacking, or weakened framework stability. Here, we report a pore size expansion strategy by self-recognizing π-π stacking interactions in a series of two-dimensional (2D) hydrogen–bonded organic frameworks (HOFs), HOF-10x (x=0,1,2), self-assembled from pyrene-based tectons with systematic elongation of π-conjugated molecular arms. This strategy successfully avoids interpene-tration or staggered stacking and expands the pore size of HOF materials to access mesoporous HOF-102, which features a surface area of ~ 2,500 m2/g and the largest pore volume (1.3 cm3/g) to date among all reported HOFs. More importantly, HOF-102 shows significantly enhanced thermal and chemical stability as evidenced by powder x-ray diffraction and N2 isotherms after treatments in chal-lenging conditions. Such stability enables the adsorption of dyes and cytochrome c from aqueous media by HOF-102 and affords a processible HOF-102/fiber composite for the efficient photochemical detox-ification of a mustard gas simulant.

Hetero-Tricyclic Lead Scaffold as Novel PDE5A Inhibitor for Antihypertensive Activity: In Silico Docking Studies

2019 ◽  
Vol 15 (4) ◽  
pp. 318-333
Author(s):  
Dipak P. Mali ◽  
Neela M. Bhatia
Keyword(s):  
In Silico ◽  
Docking Study ◽  
Docking Studies ◽  
Antihypertensive Activity ◽  
In Silico Docking ◽  
Π Stacking ◽  
Π Stacking Interaction ◽  
Nitrogen Heteroatom ◽  
Inhibitory Potential ◽  
Vlife Mds

Objective:To screen the phytochemicals for phosphodiesterase 5A (PDE5A) inhibitory potential and identify lead scaffolds of antihypertensive phytochemicals using in silico docking studies.Methods:In this perspective, reported 269 antihypertensive phytochemicals were selected. Sildenafil, a PDE5A inhibitor was used as the standard. In silico docking study was carried out to screen and identify the inhibiting potential of the selected phytochemicals against PDE5A enzyme using vLife MDS 4.4 software.Results:Based on docking score, π-stacking, H-bond and ionic interactions, 237 out of 269 molecules were selected which have shown one or more interactions. Protein residue Gln817A was involved in H-boding whereas Val782A, Phe820A and Leu804A were involved in π-stacking interaction with ligand. The selected 237 phytochemicals were structurally diverse, therefore 82 out of 237 molecules with one or more tricycles were filtered out for further analysis. Amongst tricyclic molecules, 14 molecules containing nitrogen heteroatom were selected for lead scaffold identification which finally resulted in three different basic chemical backbones like pyridoindole, tetrahydro-pyridonaphthyridine and dihydro-pyridoquinazoline as lead scaffolds.Conclusion:In silico docking studies revealed that nitrogen-containing tetrahydro-pyridonaphthyridine and dihydro-pyridoquinazoline tricyclic lead scaffolds have emerged as novel PDE5A inhibitors for antihypertensive activity. The identified lead scaffolds may provide antihypertensive lead molecules after its optimization.

The 1-Naphthol Dimer and Its Surprising Preference for π–π Stacking over Hydrogen Bonding

2019 ◽  
Vol 10 (11) ◽  
pp. 2836-2841 ◽  
Author(s):  
Nathan A. Seifert ◽  
Arsh S. Hazrah ◽  
Wolfgang Jäger
Keyword(s):  
Hydrogen Bonding ◽  
Π Stacking

scholarly journals Heteroleptic [Cu(P^P)(N^N)][PF6] Complexes: Effects of Isomer Switching from 2,2′-biquinoline to 1,1′-biisoquinoline

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 185
Author(s):  
Nina Arnosti ◽  
Marco Meyer ◽  
Alessandro Prescimone ◽  
Edwin C. Constable ◽  
Catherine E. Housecroft
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Nmr Spectra ◽  
Phenyl Ether ◽  
Quantum Yields ◽  
Dynamic Processes ◽  
Electrochemical Behaviors ◽  
Ambient Temperatures ◽  
Π Stacking

The preparation and characterization of [Cu(POP)(biq)][PF6] and [Cu(xantphos)(biq)][PF6] are reported (biq = 1,1′-biisoquinoline, POP = bis(2-(diphenylphosphanyl)phenyl)ether, and xantphos = (9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphane). The single crystal structure of [Cu(POP)(biq)][PF6] 0.5Et2O was determined and compared to that in three salts of [Cu(POP)(bq)]+ in which bq = 2,2′-biquinoline. The P–C–P angle is 114.456(19)o in [Cu(POP)(biq)]+ compared to a range of 118.29(3)–119.60(3)o [Cu(POP)(bq)]+. There is a change from an intra-POP PPh2-phenyl/(C6H4)2O-arene π-stacking in [Cu(POP)(biq)]+ to a π-stacking contact between the POP and bq ligands in [Cu(POP)(bq)]+. In solution and at ambient temperatures, the [Cu(POP)(biq)][PF6]+ and [Cu(xantphos)(biq)]+ cations undergo several concurrent dynamic processes, as evidenced in their multinuclear NMR spectra. The photophysical and electrochemical behaviors of the heteroleptic copper (I) complexes were investigated, and the effects of changing from bq to biq are described. Short Cu···O distances within the [Cu(POP)(biq)]+ and [Cu(xantphos)(biq)]+ cations may contribute to their very low photoluminescent quantum yields.

2,6-Dibromogallates as a new building block for controlling π-stacking, network formation and mirror symmetry breaking

2021 ◽  
Author(s):  
Ohjin Kwon ◽  
Xiaoqian Cai ◽  
Azhar Saeed ◽  
Feng Liu ◽  
Silvio Poppe ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Building Block ◽  
Mirror Symmetry ◽  
Network Formation ◽  
Network Structures ◽  
Π Stacking ◽  
Bicontinuous Cubic ◽  
Substituted 1 ◽  
End Group

Achiral multi-chain (polycatenar) compounds based on the 2,7-diphenyl substituted [1]benzothieno[3,2-b]benzothiophene (BTBT) unit and a 2,6-dibromo-3,4,5-trialkoxybenzoate end group lead to materials forming bicontinuous cubic liquid crystaline phases with helical network structures...

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