scholarly journals Fluorinated azobenzenes as supramolecular halogen-bonding building blocks

2019 ◽  
Vol 15 ◽  
pp. 2013-2019 ◽  
Author(s):  
Esther Nieland ◽  
Oliver Weingart ◽  
Bernd M Schmidt
Keyword(s):  
Solid State ◽  
Dft Calculations ◽  
Visible Light ◽  
Half Life ◽  
Photophysical Properties ◽  
Bathochromic Shift ◽  
Halogen Bonding ◽  
Building Blocks ◽  
Partial Overlap

ortho-Fluoroazobenzenes are a remarkable example of bistable photoswitches, addressable by visible light. Symmetrical, highly fluorinated azobenzenes bearing an iodine substituent in para-position were shown to be suitable supramolecular building blocks both in solution and in the solid state in combination with neutral halogen bonding acceptors, such as lutidines. Therefore, we investigate the photochemistry of a series of azobenzene photoswitches. Upon introduction of iodoethynyl groups, the halogen bonding donor properties are significantly strengthened in solution. However, the bathochromic shift of the π→π* band leads to a partial overlap with the n→π* band, making it slightly more difficult to address. The introduction of iodine substituents is furthermore accompanied with a diminishing thermal half-life. A series of three azobenzenes with different halogen bonding donor properties are discussed in relation to their changing photophysical properties, rationalized by DFT calculations.

σ-Hole halogen bonding interactions in a mixed valence cobalt(iii/ii) complex and anti-electrostatic hydrogen bonding interaction in a cobalt(iii) complex: a theoretical insight

CrystEngComm ◽  
2018 ◽  
Vol 20 (45) ◽  
pp. 7281-7292 ◽  
Author(s):  
Kousik Ghosh ◽  
Klaus Harms ◽  
Antonio Bauzá ◽  
Antonio Frontera ◽  
Shouvik Chattopadhyay
Keyword(s):  
Hydrogen Bonding ◽  
Solid State ◽  
Dft Calculations ◽  
Mixed Valence ◽  
Halogen Bonding ◽  
Supramolecular Interactions ◽  
Hydrogen Bonding Interaction ◽  
Bonding Interaction ◽  
Solid State Structures ◽  
Theoretical Insight

Supramolecular interactions in the solid state structures of a mixed valence cobalt(ii/iii) complex and a cobalt(iii) complex have been studied using DFT calculations.

Halogen-bonding in a new family of tris(haloanilato)metallate(iii) magnetic molecular building blocks

2014 ◽  
Vol 43 (19) ◽  
pp. 7006-7019 ◽  
Author(s):  
Matteo Atzori ◽  
Flavia Artizzu ◽  
Elisa Sessini ◽  
Luciano Marchiò ◽  
Danilo Loche ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Dft Calculations ◽  
Crystal Structures ◽  
General Formula ◽  
Halogen Bonding ◽  
Building Blocks ◽  
New Family ◽  
Molecular Building Blocks

Here we report on new tris(haloanilato)metallate(iii) complexes with general formula [M(X2An)3]3−, their crystal structures, DFT calculations and magnetic properties.

scholarly journals Polyhalides as scaffolds for supramolecular, ion-conducting crown ether stacks

2014 ◽  
Vol 70 (a1) ◽  
pp. C634-C634
Author(s):  
Katharina Fromm ◽  
Aurélien Crochet ◽  
Cyrille Dagri ◽  
Yvens Chérémond
Keyword(s):  
Solid State ◽  
Single Crystal ◽  
Crown Ethers ◽  
Halogen Bonding ◽  
Building Blocks ◽  
Channel Formation ◽  
One Dimensional ◽  
Naoh Solution ◽  
Ion Conducting

"Crown ethers, such as dibenzo-18-crown-6 (DB18C6) are in principle perfect building blocks to be stacked on top of each other for one-dimensional (1D) channel formation. However, in the more than 1000 publications on crown ethers in the solid state, only one case was of channel formation described, but not as main focus of research.[1] We now present a way to systematically induce the stacking of DB18C6 with the help of polyhalides, which play the roles of scaffolds via halogen bonding.[2] These compounds can be considered as ""supramolecular straws"". Using for example potassium as couter ion for triiodide for example, we obtained a solid which contains three differently filled, parallel channels in the solid state, which are arranged between the polyhalide anions. Exchanging potassium with sodium by immersion of a single crystal into NaOH solution leads to a single-crystal-to-single-crystal transformation into a compound with two channel types. This transition from a system crystallizing initially in the P2-space group to yield a compound in Pccn is only possible under these very special conditions. We will further present how the ion transport through these channels can be quantified and which process is involved in ion exchange. The role of the polyhalide anions, which cannot be replaced by other linear anions, will be emphasized as well. "

Anionic Cyclometallated platinum(II) Tetrazolato Complexes as Viable Photoredox Catalysts

2018 ◽  
Author(s):  
Anna Maria Ranieri ◽  
Liam Burt ◽  
Stefano Stagni ◽  
Stefano Zacchini ◽  
Brian Skelton ◽  
...  
Keyword(s):  
Solid State ◽  
Visible Light ◽  
Room Temperature ◽  
Functional Group ◽  
Photophysical Properties ◽  
General Structure ◽  
No Emission ◽  
Michael Acceptors ◽  
Catalyzed Reactions

The synthesis, characterization, photophysical and photocatalytic studies of anionic platinum(II) tetrazolato complexes, with the general structure [TBA][Pt(CNC)TzR], are reported, where CNC<sup>2-</sup>represents a doubly cyclometalated 2,4,6-triphenylpyridine, TzR<sup>- </sup>is an anionic 5-substituted tetrazolato ligand (with a variable R functional group) and TBA<sup>+ </sup>is the tetrabutylammonium countercation. The complexes were prepared by substitution of the DMSO ligand in [Pt(CNC)(DMSO)] with the corresponding tetrazolato ligand. No emission from the platinum(II) complexes was detected at room temperature in solution, but the photophysical properties could be assessed in the solid state, where all the complexes display emission bands attributed to aggregates. The platinum(II) complexes were found to facilitate a range of fundamental classes of visible-light-mediated photoredox-catalyzed reactions, including α‑amino C–H functionalization processes, such as Povarov-type reactions and the addition of α-amino C–H bonds across Michael acceptors, in addition to ATRA chemistry, and a hydrodeiodination. With the exception of the hydrodeiodination process, the best Pt(II) catalysts provided turnover numbers of 150–175 in each of these transformations.

π-Conjugated diimidazolium salts: rigid structure to obtain organized materials

2015 ◽  
Vol 17 (40) ◽  
pp. 26903-26917 ◽  
Author(s):  
Paola Vitale ◽  
Francesca D'Anna ◽  
Francesco Ferrante ◽  
Carla Rizzo ◽  
Renato Noto
Keyword(s):  
Solid State ◽  
Dft Calculations ◽  
Photophysical Properties ◽  
Experimental Investigations ◽  
Rigid Structure

The photophysical properties and aggregation ability of π-conjugated diimidazolium salts were studied in solution and in the solid state. Experimental investigations were supported by DFT calculations.

Ta-substituted SnNb2−xTaxO6 photocatalysts for hydrogen evolution under visible light irradiation

2015 ◽  
Vol 3 (2) ◽  
pp. 825-831 ◽  
Author(s):  
Chan Woo Lee ◽  
Hoon Kee Park ◽  
Sangbaek Park ◽  
Hyun Soo Han ◽  
Se Won Seo ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Visible Light ◽  
Hydrogen Evolution ◽  
Visible Light Irradiation ◽  
Solid State Reaction ◽  
Photophysical Properties ◽  
Light Irradiation ◽  
Photocatalytic Activities

Ta-substituted SnNb2−xTaxO6 was successfully prepared via a solid-state reaction to study the effect of Ta insertion in Nb sites on the crystal structure, photophysical properties, and photocatalytic activities for hydrogen evolution.

scholarly journals “Anti-Electrostatic” Halogen Bonding

2020 ◽  
Author(s):  
Jana Holthoff ◽  
Elric Engelage ◽  
Robert Weiss ◽  
Stefan Huber
Keyword(s):  
Solid State ◽  
Dft Calculations ◽  
Gas Phase ◽  
Electrostatic Potential ◽  
Lewis Acids ◽  
Halogen Bonding ◽  
Halide Complexes ◽  
Self Association ◽  
Solid State Structures ◽  
Van Der Waals Radii

Halogen bonding (XB) is often described as being driven predominantly by electrostatics, and thus adducts between <i>anionic</i> XB donors (halogen-based Lewis acids) and anions seem counter­intuitive. Such “anti-electrostatic” XBs have been predicted theoretically, but there are currently no experimental examples based on organic XB donors. Herein, we report the synthesis of two negatively charged organoiodine derivatives, which were subsequently investigated towards their ability to form “anti-electrostatic” XBs with anions. Even though the electrostatic potential is universally negative across the surface of both compounds, DFT calculations indicate kinetic stabilization of their halide complexes in the gas phase and particularly in solution. Experimentally, self-association of the anionic XB donors was observed in solid-state structures, resulting in dimers, trimers and infinite chains. In addition, co-crystals with halides were obtained which featured XB adducts between two or even three anions. The bond-lengths of all observed interactions are 14-21% shorter than sum of the van-der-Waals radii.

Anionic Cyclometallated platinum(II) Tetrazolato Complexes as Viable Photoredox Catalysts

2018 ◽  
Author(s):  
Anna Maria Ranieri ◽  
Liam Burt ◽  
Stefano Stagni ◽  
Stefano Zacchini ◽  
Brian Skelton ◽  
...  
Keyword(s):  
Solid State ◽  
Visible Light ◽  
Room Temperature ◽  
Functional Group ◽  
Photophysical Properties ◽  
General Structure ◽  
No Emission ◽  
Michael Acceptors ◽  
Catalyzed Reactions

The synthesis, characterization, photophysical and photocatalytic studies of anionic platinum(II) tetrazolato complexes, with the general structure [TBA][Pt(CNC)TzR], are reported, where CNC<sup>2-</sup>represents a doubly cyclometalated 2,4,6-triphenylpyridine, TzR<sup>- </sup>is an anionic 5-substituted tetrazolato ligand (with a variable R functional group) and TBA<sup>+ </sup>is the tetrabutylammonium countercation. The complexes were prepared by substitution of the DMSO ligand in [Pt(CNC)(DMSO)] with the corresponding tetrazolato ligand. No emission from the platinum(II) complexes was detected at room temperature in solution, but the photophysical properties could be assessed in the solid state, where all the complexes display emission bands attributed to aggregates. The platinum(II) complexes were found to facilitate a range of fundamental classes of visible-light-mediated photoredox-catalyzed reactions, including α‑amino C–H functionalization processes, such as Povarov-type reactions and the addition of α-amino C–H bonds across Michael acceptors, in addition to ATRA chemistry, and a hydrodeiodination. With the exception of the hydrodeiodination process, the best Pt(II) catalysts provided turnover numbers of 150–175 in each of these transformations.

scholarly journals “Anti-Electrostatic” Halogen Bonding

2020 ◽  
Author(s):  
Jana Holthoff ◽  
Elric Engelage ◽  
Robert Weiss ◽  
Stefan Huber
Keyword(s):  
Solid State ◽  
Dft Calculations ◽  
Gas Phase ◽  
Electrostatic Potential ◽  
Lewis Acids ◽  
Halogen Bonding ◽  
Halide Complexes ◽  
Self Association ◽  
Solid State Structures ◽  
Van Der Waals Radii

Halogen bonding (XB) is often described as being driven predominantly by electrostatics, and thus adducts between <i>anionic</i> XB donors (halogen-based Lewis acids) and anions seem counter­intuitive. Such “anti-electrostatic” XBs have been predicted theoretically, but there are currently no experimental examples based on organic XB donors. Herein, we report the synthesis of two negatively charged organoiodine derivatives, which were subsequently investigated towards their ability to form “anti-electrostatic” XBs with anions. Even though the electrostatic potential is universally negative across the surface of both compounds, DFT calculations indicate kinetic stabilization of their halide complexes in the gas phase and particularly in solution. Experimentally, self-association of the anionic XB donors was observed in solid-state structures, resulting in dimers, trimers and infinite chains. In addition, co-crystals with halides were obtained which featured XB adducts between two or even three anions. The bond-lengths of all observed interactions are 14-21% shorter than sum of the van-der-Waals radii.

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