Porphyrin tripod as a monomeric building block for guest-induced reversible supramolecular polymerisation

Abstract Reversible supramolecular polymerisation and depolymerisation of biomacromolecules are common and fundamental phenomena in biological systems, which can be controlled by the selective modification of biomacromolecules through molecular recognition. Herein, a porphyrin tripod (DPZnT) connected through a triazole bridge was prepared as a monomeric building block for guest-induced supramolecular polymerisation. Although the lone pair electrons in triazolic nitrogen potentially bind to the zinc porphyrin units through axial ligation, the intrinsic steric hindrance suppressed the coordination of the triazole bridge to the porphyrin unit in DPZnT. Therefore, DPZnT formed spherical nanoparticles through π-π interactions. The addition of 1,3,5-tris(pyridine-4-yl)benzene (Py3B) caused the guest-induced fibrous supramolecular polymerisation of DPZnT by forming a 1:1 host-guest complex, which was further assembled into a fibrous polymer. Furthermore, addition of Cl− to DPZnT induced the transformation of spherical nanoparticles to fibrous supramolecular polymers. The fibrous supramolecular polymers of DPZnT obtained by adding Py3B or Cl− were depolymerised to their original spherical particles after adding Cu(ClO4)2 or AgNO3, respectively.

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Illustration of a computational pipeline for evaluating cyclodextrin host–guest complex formation through conformational capture of bullvalene

The Journal of Chemical Physics ◽

10.1063/5.0045115 ◽

2021 ◽

Vol 154 (15) ◽

pp. 154105

Author(s):

Zahra Shadfar ◽

Oussama Yahiaoui ◽

Thomas A. Collier ◽

Thomas Fallon ◽

Jane R. Allison

Keyword(s):

Complex Formation ◽

Computational Pipeline ◽

Guest Complex ◽

Host Guest Complex

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Effect of delocalization of nonbonding electron density on the stability of the M–Ccarbene bond in main group metal-imidazol-2-ylidene complexes: a computational and structural database study

Physical Sciences Reviews ◽

10.1515/psr-2020-0084 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Samuel Tetteh ◽

Albert Ofori

Keyword(s):

Electron Density ◽

Lone Pair ◽

Main Group ◽

Binding Energies ◽

Electrostatic Model ◽

Group Metal ◽

Main Group Metal ◽

Structural Database ◽

The Stability ◽

Lone Pair Electrons

Abstract The M–Ccarbene bond in metal (M) complexes involving the imidazol-2-ylidene (Im) ligand has largely been described using the σ-donor only model with donation of σ electrons from the sp-hybridized orbital of the carbene carbon into vacant orbitals on the metal centre. Analyses of the M–Ccarbene bond in a series of group IA, IIA and IIIA main group metal complexes show that the M-Im interactions are mostly electrostatic with the M–Ccarbene bond distances greater than the sum of the respective covalent radii. Estimation of the binding energies of a series of metal hydride/fluoride/chloride imidazol-2-ylidene complexes revealed that the stability of the M–Ccarbene bond in these complexes is not always commensurate with the σ-only electrostatic model. Further natural bond orbital (NBO) analyses at the DFT/B3LYP level of theory revealed substantial covalency in the M–Ccarbene bond with minor delocalization of electron density from the lone pair electrons on the halide ligands into antibonding molecular orbitals on the Im ligand. Calculation of the thermodynamic stability of the M–Ccarbene bond showed that these interactions are mostly endothermic in the gas phase with reduced entropies giving an overall ΔG > 0.

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Long-term stability in γ-CsPbI3 perovskite via an ultraviolet-curable polymer network

Communications Materials ◽

10.1038/s43246-021-00134-1 ◽

2021 ◽

Vol 2 (1) ◽

Author(s):

Nam-Kwang Cho ◽

Hyun-Jae Na ◽

Jeeyoung Yoo ◽

Youn Sang Kim

Keyword(s):

Polymer Network ◽

Lone Pair ◽

Ambient Conditions ◽

Absorption Properties ◽

Term Stability ◽

Long Term Stability ◽

Ultraviolet Curable ◽

Oxygen Lone Pair ◽

Lone Pair Electrons

AbstractBlack-colored (α, γ-phase) CsPbI3 perovskites have a small bandgap and excellent absorption properties in the visible light regime, making them attractive for solar cells. However, their long-term stability in ambient conditions is limited. Here, we demonstrate a strategy to improve structural and electrical long-term stability in γ-CsPbI3 by the use of an ultraviolet-curable polyethylene glycol dimethacrylate (PEGDMA) polymer network. Oxygen lone pair electrons from the PEGDMA are found to capture Cs+ and Pb2+ cations, improving crystal growth of γ-CsPbI3 around PEGDMA. In addition, the PEGDMA polymer network strongly contributes to maintaining the black phase of γ-CsPbI3 for more than 35 days in air, and an optimized perovskite film retained ~90% of its initial electrical properties under red, green, and blue light irradiation.

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Columnar one-dimensional coordination polymer formed with a metal ion and a host–guest complex as building blocks: potassium ion complexed cucurbituril

Inorganica Chimica Acta ◽

10.1016/s0020-1693(99)00318-7 ◽

2000 ◽

Vol 297 (1-2) ◽

pp. 307-312 ◽

Cited By ~ 77

Author(s):

Jungseok Heo ◽

Jaheon Kim ◽

Dongmok Whang ◽

Kimoon Kim

Keyword(s):

Coordination Polymer ◽

Metal Ion ◽

Building Blocks ◽

Potassium Ion ◽

Guest Complex ◽

One Dimensional ◽

Host Guest Complex

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VUV FRAGMENTATION OF SOME HYDROFLUOROCARBON CATIONS STUDIED USING COINCIDENCE TECHNIQUES

Surface Review and Letters ◽

10.1142/s0218625x0200204x ◽

2002 ◽

Vol 09 (01) ◽

pp. 153-158 ◽

Cited By ~ 5

Author(s):

WEIDONG ZHOU ◽

D. P. SECCOMBE ◽

R. Y. L. CHIM ◽

R. P. TUCKETT

Keyword(s):

Kinetic Energy ◽

Ab Initio ◽

Ground State ◽

Lower Energy ◽

Lone Pair ◽

Electronic States ◽

Photoelectron Spectra ◽

Highest Occupied Molecular Orbital ◽

Impulsive Model ◽

Lone Pair Electrons

Threshold photoelectron–photoion coincidence (TPEPICO) spectroscopy has been used to investigate the decay dynamics of the valence electronic states of the parent cation of several hydrofluorocarbons (HFC), based on fluorine-substituted ethane, in the energy range 11–25 eV. We present data for CF 3– CHF 2, CF 3– CH 2 F , CF 3– CH 3 and CHF 2– CH 3. The threshold photoelectron spectra (TPES) of these molecules show a common feature of a broad, relatively weak ground state, associated with electron removal from the highest-occupied molecular orbital (HOMO) having mainly C–C σ-bonding character. Adiabatic and vertical ionisation energies for the HOMO of the four HFCs are presented, together with corresponding values from ab initio calculations. For those lower-energy molecular orbitals associated with non-bonding fluorine 2pπ lone pair electrons, these electronic states of the HFC cation decay impulsively by C–F bond fission with considerable release of translational kinetic energy. Appearance energies are presented for formation of the daughter cation formed by such a process (e.g. CF 3– CHF +), together with ab initio energies of the corresponding dissociation channel (e.g. CF 3– CHF + + F ). Values for the translational kinetic energy released are compared with the predictions of a pure-impulsive model.

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The molecular orbital theory of chemical valency. V. The structure of water and similar molecules

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1950.0103 ◽

1950 ◽

Vol 202 (1070) ◽

pp. 323-336 ◽

Cited By ~ 97

Keyword(s):

Spatial Distribution ◽

Equilibrium Configuration ◽

Bond Angle ◽

Lone Pair ◽

Orbital Theory ◽

Hydrogen Atoms ◽

Molecular Formation ◽

Major Factors ◽

Lone Pair Electrons ◽

Electrostatic Repulsions

The theory of molecular and equivalent orbitals developed in previous papers of this series is used to discuss the spatial distribution of lone-pair electrons in molecules such as H 2 O and NH 3 and the part they play in determining the equilibrium configuration. Previous treatments of H 2 O have assumed that the lone pairs are essentially unaltered by molecular formation. It is shown here, on the other hand, that they will be displaced so as to be mainly concentrated on the side of the O-nucleus remote from the hydrogen atoms. An important consequence of this is that the lone-pair electrons will make a contribution to the total dipole moment. Comparison of the experimentally observed moment with an approximate quantitative treatment suggests that, as a result of this, transfer of electrons from the hydrogen atoms to the oxygen does not occur to the extent that has previously been believed. The variation of the spatial distribution of the orbitals of H 2 O with changes of nuclear configuration is examined and it is shown that, in the equilibrium position, the electronic structure can be described approximately by two sets of two equivalent orbitals pointing in nearly tetrahedral directions. The dependence of total energy on bond angle is discussed and it is shown that electrostatic repulsions between the equivalent orbitals are major factors in determining the equilibrium configuration. Similar considerations apply to NH 3 .

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p-Type conductivity of GeTe: The role of lone-pair electrons

physica status solidi (b) ◽

10.1002/pssb.201200434 ◽

2012 ◽

Vol 249 (10) ◽

pp. 1902-1906 ◽

Cited By ~ 9

Author(s):

Alexander V. Kolobov ◽

Paul Fons ◽

Junji Tominaga

Keyword(s):

Lone Pair ◽

Type Conductivity ◽

P Type ◽

Lone Pair Electrons

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Wet-etched asymmetric spherical nanoparticles with controllable pit structure and application in non-aqueous foam

Soft Matter ◽

10.1039/d0sm01964j ◽

2021 ◽

Author(s):

Gen Li ◽

Keliang Wang ◽

Chunjing Lu

Keyword(s):

Colloidal Particles ◽

Spherical Particles ◽

Spherical Nanoparticles ◽

Aqueous Foam ◽

Wet Chemical

The structure of colloidal particles is one of the factors that significantly affect their properties. Asymmetrical spherical particles with pit structures were prepared by using NH4F to perform wet chemical...

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