scholarly journals A BODIPY-Bridged Bisphenoxyl Diradicaloid: Solvent-Dependent Diradical Character and Physical Properties

Molecules ◽  
2019 ◽  
Vol 24 (8) ◽  
pp. 1446 ◽  
Author(s):  
Fang Miao ◽  
Hoa Phan ◽  
Jishan Wu
Keyword(s):  
Polar Solvent ◽  
Closed Shell ◽  
Dipole Interaction ◽  
Open Shell ◽  
Crystallographic Analysis ◽  
Structural Flexibility ◽  
Polar Solvents ◽  
X Ray ◽  
Diradical Character ◽  
Paramagnetic Activity

We report a new boron dipyrromethene (BODIPY)-bridged bisphenoxyl diradicaloid (2), which showed closed-shell diamagnetic character in less polar solvents such as dichloromethane but open-shell diradical character with paramagnetic activity in the very polar solvent N,N-dimethylformamide. X-ray crystallographic analysis of 2 revealed an anti-parallel stacked dimer structure via intermolecular dipole–dipole interaction, and the observed solvent-dependent diradical character can be explained by the different dihedral angles between the phenoxyl units and the BODIPY bridge, and structural flexibility of the molecule in different solvents. Compound 2 also exhibited solvent-dependent optical and electrochemical properties.

scholarly journals Evolution of the electronic structure in open-shell donor-acceptor organic semiconductors

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zhongxin Chen ◽  
Wenqiang Li ◽  
Md Abdus Sabuj ◽  
Yuan Li ◽  
Weiya Zhu ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Organic Semiconductors ◽  
High Performance ◽  
Closed Shell ◽  
Open Shell ◽  
Ground State Structure ◽  
Structure Property ◽  
System A ◽  
Diradical Character ◽  
Donor Acceptor

AbstractMost organic semiconductors have closed-shell electronic structures, however, studies have revealed open-shell character emanating from design paradigms such as narrowing the bandgap and controlling the quinoidal-aromatic resonance of the π-system. A fundamental challenge is understanding and identifying the molecular and electronic basis for the transition from a closed- to open-shell electronic structure and connecting the physicochemical properties with (opto)electronic functionality. Here, we report donor-acceptor organic semiconductors comprised of diketopyrrolopyrrole and naphthobisthiadiazole acceptors and various electron-rich donors commonly utilized in constructing high-performance organic semiconductors. Nuclear magnetic resonance, electron spin resonance, magnetic susceptibility measurements, single-crystal X-ray studies, and computational investigations connect the bandgap, π-extension, structural, and electronic features with the emergence of various degrees of diradical character. This work systematically demonstrates the widespread diradical character in the classical donor-acceptor organic semiconductors and provides distinctive insights into their ground state structure-property relationship.

Ca–Ca interaction in inverse sandwich Ca–C8H8–Ca

2015 ◽  
Vol 44 (1) ◽  
pp. 345-350 ◽  
Author(s):  
Nan-nan Liu ◽  
Si-meng Gao ◽  
Yi-hong Ding
Keyword(s):  
Dimethyl Ether ◽  
Closed Shell ◽  
Open Shell ◽  
Diradical Character

The inverse sandwich Ca–C8H8–Ca is predicted to be open-shell singlet Ca–C8H8–Ca. The singlet diradical character is caused by the C8H8 ligand preventing the spin-paired electrons of different calcium atoms from forming Ca–Ca bonds. A direct Ca–Ca bond is favorable in closed-shell singlet (DME)3Ca–C8H8–Ca(DME)3, because dimethyl ether molecules could push the spin-paired electrons of different calcium atoms to migrate towards the direction of Ca–Ca bonding.

scholarly journals Anti-ohmic Nanoconductors: Myth, Reality and Promise

2021 ◽  
Author(s):  
Ashima Bajaj ◽  
Md. Ehesan Ali
Keyword(s):  
Symmetry Breaking ◽  
Ground State ◽  
Closed Shell ◽  
Open Shell ◽  
Molecular Junctions ◽  
Spatial Symmetry ◽  
New Family ◽  
Diradical Character ◽  
Classical Behavior

The recent accomplishments in the design of molecular nanowires characterised by an increasing conductance with length has embarked the origin of extraordinary new family of molecular junctions referred to as "anti-ohmic" wires. Herein, this highly desirable, non-classical behavior, has been examined for the longer enough molecules exhibiting pronounced diradical character in their ground state within the unrestricted DFT formalism with spin and spatial symmetry breaking. We demonstrate that highly conjugated acenes signals higher resistance in open-shell singlet (OSS) configuration as compared to their closed-shell counterparts. This anomaly has been further put to proof for experimentally certified cumulene wires, which reveals phenomenal modulation in the transport characteristics such that an increasing conductance is observed in closed-shell limit, while higher cumulenes in OSS ground state yields a regular decay of conductance.

Discotic liquid crystals of transition metal complexes 46: mesomorphism and antagonist solubility of octaphenoxy-phthalocyaninato copper(II) complex substituted by oligoether chains

2012 ◽  
Vol 16 (11) ◽  
pp. 1209-1216 ◽  
Author(s):  
Hiroyuki Sato ◽  
Yuya Sakagami ◽  
Eiji Itoh ◽  
Kazuchika Ohta
Keyword(s):  
Liquid Crystalline ◽  
Polar Solvent ◽  
Optical Microscope ◽  
Discotic Liquid Crystals ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Polar Solvents ◽  
X Ray ◽  
Virgin Sample ◽  
Liquid Crystalline Compound

We synthesized a novel discotic liquid crystalline compound, octakis[3-(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)phenoxy]phthalocyaninato copper(II) (abbreviated as [m- MeO(EtO)3PhO]8PcCu ), and established the mesomorphism by using a differential scanning calorimeter, a polarizing optical microscope, and temperature-dependent wide angle X-ray diffraction diffractometer. Very interestingly, this [m- MeO(EtO)3PhO]8PcCu complex showed a hexagonal ordered columnar (Colho) mesophase in the virgin sample, whereas it showed a rectangular ordered columnar (Colro(P21/a)) mesophase in the non-virgin sample. The Colho mesophase gave a dimer stacking distance at 9.26 Å, whereas the Colro mesophase gave a short monomer stacking distance at 3.45 Å. Furthermore, this novel Pc derivative is readily soluble in polar solvents such as acetone, ethanol and methanol. Using antagonist solubilities of the present hydrophilic [m- MeO(EtO)3PhO]8PcCu derivative in a polar solvent and the previous hydrophobic (C10O)16TzCu derivative in the non-polar solvent, a p-n junction layered thin films could be successfully prepared.

Nature ofE2X2σ(4c–6e) of theX---E—E---Xtype at naphthalene 1,8-positions and model, elucidated by X-ray crystallographic analysis and QC calculations with the QTAIM approach

2017 ◽  
Vol 73 (2) ◽  
pp. 265-275 ◽  
Author(s):  
Yutaka Tsubomoto ◽  
Satoko Hayashi ◽  
Waro Nakanishi ◽  
Takahiro Sasamori ◽  
Norihiro Tokitoh
Keyword(s):  
Closed Shell ◽  
Crystallographic Analysis ◽  
Dynamic Nature ◽  
Total Electron ◽  
X Ray ◽  
Dual Functional ◽  
Total Electron Energy ◽  
Polar Coordinate ◽  
Static Nature

The nature ofE2X2σ(4c–6e) of theX-*-E-*-E-*-Xtype is elucidated for 1-(8-XC10H6)E–E(C10H6X-8′)-1′ [(1)E,X= S, Cl; (2) S, Br; (3) Se, Cl; (4) Se, Br] after structural determination of (1), (3) and (4), together with modelA[MeX---E(H)—E(H)---XMe (E= S and Se;X= Cl and Br)]. The quantum theory of atoms-in-molecules dual functional analysis (QTAIM-DFA) is applied. The total electron energy densitiesHb(rc) are plottedversus Hb(rc) –Vb(rc)/2 for the interactions at the bond critical points (BCPs; *), whereVb(rc) show the potential energy densities at the BCPs. Data for the perturbed structures around the fully optimized structures are employed for the plots, in addition to those of the fully optimized structures. The plots were analysed using the polar coordinate (R, θ) representation of the data of the fully optimized structures. Data containing the perturbed structures were analysed by (θp, κp), where θpcorresponds to the tangent line of the plot and κpis the curvature. Whereas (R, θ) shows the static nature, (θp, κp) represents the dynamic nature of interactions.E-*-Eare all classified as shared shell (S) interactions for (1)–(4) and as weak covalent (Cov-w) in nature (S/Cov-w). The nature ofpureCS (closed shell)/typical-HB (hydrogen bond) with no covalency is predicted forE-*-Xin (1) and (3),regularCS/typical-HB nature with covalency is predicted for (4), and an intermediate nature is predicted for (2). The NBO energies evaluated forE-*-Xin (1)–(4) are substantially larger than those in modelAdue the shortened length at the naphthalene 1,8-positions. The nature ofE2X2of σ(4c–6e) is well elucidatedviaQTAIM-DFA.

INSIGHTS INTO THE SOLVATO-/THERMO-PROMOTED INTRAMOLECULAR ELECTRON TRANSFER IN A TTF-σ-TCNQ DYAD WITH AN EXTREMELY LOW HOMO–LUMO GAP

2012 ◽  
Vol 11 (03) ◽  
pp. 599-609 ◽  
Author(s):  
YUHUA ZHOU ◽  
KAI TAN ◽  
XIN LU
Keyword(s):  
Electron Transfer ◽  
Gas Phase ◽  
Ground State ◽  
Polar Solvent ◽  
Closed Shell ◽  
Open Shell ◽  
Polarizable Continuum Model ◽  
Intramolecular Electron Transfer ◽  
Singlet Ground State ◽  
Solvent Polarization

The low-lying states of an organic donor-σ-acceptor dyad, i.e. tetrathiafulvalene-σ-tetracyano-p-quinodimethane (TTF-σ-TCNQ), in gas phase and in various solvents have been investigated by means of hybrid DFT calculations in combination with the conductor-like polarizable continuum model to describe solvent effects. It has been shown that the dyad, though preferring a closed-shell singlet ground state with an eclipsed conformation in gas phase, adopts the charge-separated zwitterionic states with an extended conformation (TTF+-σ-TCNQ-), i.e. open-shell singlet biradical ground state immediately followed by triplet biradical state, in polar solvent ( CH3CN and CH2Cl2 ) as a result of the intramolecular electron transfer (ET) stimulated by solvent polarization. The degree of such intramolecular ET is so strongly dependent on the polarity (dielectric constant) of solvent that the zwitterionic biradical states become more stable with respect to the closed-shell singlet state with increasing polarity of the solvent. As such, the dyad should show a higher ratio of biradicals in more polar solvent and/or at higher temperature and, hence, is chameleonic in nature.

Quaternary structure of Limulus polyphemus hemocyanin

1978 ◽  
Vol 36 (2) ◽  
pp. 176-177
Author(s):  
T. Wichertjes ◽  
E.J. Kwak ◽  
E.F.J. Van Bruggen
Keyword(s):  
Electron Microscopy ◽  
Functional Properties ◽  
Horseshoe Crab ◽  
Temperature Jump ◽  
Quaternary Structure ◽  
Crystallographic Analysis ◽  
Limulus Polyphemus ◽  
Oxygen Binding ◽  
X Ray ◽  
Intact Molecule

Hemocyanin of the horseshoe crab (Limulus polyphemus) has been studied in nany ways. Recently the structure, dissociation and reassembly was studied using electron microscopy of negatively stained specimens as the method of investigation. Crystallization of the protein proved to be possible and X-ray crystallographic analysis was started. Also fluorescence properties of the hemocyanin after dialysis against Tris-glycine buffer + 0.01 M EDTA pH 8.9 (so called “stripped” hemocyanin) and its fractions II and V were studied, as well as functional properties of the fractions by NMR. Finally the temperature-jump method was used for assaying the oxygen binding of the dissociating molecule and of preparations of isolated subunits. Nevertheless very little is known about the structure of the intact molecule. Schutter et al. suggested that the molecule possibly consists of two halves, combined in a staggered way, the halves themselves consisting of four subunits arranged in a square.

Tele-Substitution Reactions in the Synthesis of a Promising Class of Antimalarials

2020 ◽  
Author(s):  
Marat Korsik ◽  
Edwin Tse ◽  
David Smith ◽  
William Lewis ◽  
Peter J. Rutledge ◽  
...  
Keyword(s):  
Heterocyclic Ring ◽  
Ring System ◽  
Substitution Reactions ◽  
Laboratory Notebook ◽  
Polar Solvents ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Core ◽  
Nmr Data

<p></p><p>We have discovered and studied a <i>tele</i>substitution reaction in a biologically important heterocyclic ring system. Conditions that favour the <i>tele</i>-substitution pathway were identified: the use of increased equivalents of the nucleophile or decreased equivalents of base, or the use of softer nucleophiles, less polar solvents and larger halogens on the electrophile. Using results from X-ray crystallography and isotope labelling experiments a mechanism for this unusual transformation is proposed. We focused on this triazolopyrazine as it is the core structure of the <i>in vivo </i>active anti-plasmodium compounds of Series 4 of the Open Source Malaria consortium.</p> <p> </p> <p>Archive of the electronic laboratory notebook with the description of all conducted experiments and raw NMR data could be accessed via following link <a href="https://ses.library.usyd.edu.au/handle/2123/21890">https://ses.library.usyd.edu.au/handle/2123/21890</a> . For navigation between entries of laboratory notebook please use file "Strings for compounds in the article.pdf" that works as a reference between article codes and notebook codes, also this file contain SMILES for these compounds. </p><br><p></p>

Revisiting the High-Pressure Properties of the Metal-Organic Frameworks ZIF-8 and ZIF-67

2020 ◽  
Author(s):  
Pia Vervoorts ◽  
Stefan Burger ◽  
Karina Hemmer ◽  
Gregor Kieslich
Keyword(s):  
High Pressure ◽  
State Of The Art ◽  
Energy Landscape ◽  
Structural Flexibility ◽  
Zeolitic Imidazolate Frameworks ◽  
Stimuli Responsive ◽  
X Ray Diffraction ◽  
X Ray ◽  
Open Questions ◽  
Metal Organic

The zeolitic imidazolate frameworks ZIF-8 and ZIF-67 harbour a series of fascinating stimuli responsive properties. Looking at their responsitivity to hydrostatic pressure as stimulus, open questions exist regarding the isotropic compression with non-penetrating pressure transmitting media. By applying a state-of-the-art high-pressure powder X-ray diffraction setup, we revisit the high-pressure behaviour of ZIF-8 and ZIF-67 up to <i>p</i> = 0.4 GPa in small pressure increments. We observe a drastic, reversible change of high-pressure powder X-ray diffraction data at <i>p</i> = 0.3 GPa, discovering large volume structural flexibility in ZIF-8 and ZIF-67. Our results imply a shallow underlying energy landscape in ZIF-8 and ZIF-67, an observation that might point at rich polymorphism of ZIF-8 and ZIF-67, similar to ZIF-4(Zn).<br>

Revisiting the High-Pressure Properties of the Metal-Organic Frameworks ZIF-8 and ZIF-67

2020 ◽  
Author(s):  
Pia Vervoorts ◽  
Stefan Burger ◽  
Karina Hemmer ◽  
Gregor Kieslich
Keyword(s):  
High Pressure ◽  
State Of The Art ◽  
Energy Landscape ◽  
Structural Flexibility ◽  
Zeolitic Imidazolate Frameworks ◽  
Stimuli Responsive ◽  
X Ray Diffraction ◽  
X Ray ◽  
Open Questions ◽  
Metal Organic

The zeolitic imidazolate frameworks ZIF-8 and ZIF-67 harbour a series of fascinating stimuli responsive properties. Looking at their responsitivity to hydrostatic pressure as stimulus, open questions exist regarding the isotropic compression with non-penetrating pressure transmitting media. By applying a state-of-the-art high-pressure powder X-ray diffraction setup, we revisit the high-pressure behaviour of ZIF-8 and ZIF-67 up to <i>p</i> = 0.4 GPa in small pressure increments. We observe a drastic, reversible change of high-pressure powder X-ray diffraction data at <i>p</i> = 0.3 GPa, discovering large volume structural flexibility in ZIF-8 and ZIF-67. Our results imply a shallow underlying energy landscape in ZIF-8 and ZIF-67, an observation that might point at rich polymorphism of ZIF-8 and ZIF-67, similar to ZIF-4(Zn).<br>

Sign in / Sign up

Export Citation Format

Share Document