scholarly journals A chiral self-sorting photoresponsive coordination cage based on overcrowded alkenes

2019 ◽  
Vol 15 ◽  
pp. 2767-2773 ◽  
Author(s):  
Constantin Stuckhardt ◽  
Diederik Roke ◽  
Wojciech Danowski ◽  
Edwin Otten ◽  
Sander J Wezenberg ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Molecular Motors ◽  
First Generation ◽  
Substrate Binding ◽  
Coordination Complexes ◽  
Supramolecular Assemblies ◽  
Stimuli Responsive ◽  
X Ray ◽  
Supramolecular Coordination ◽  
Opening Up

In recent years, increasing efforts have been devoted to designing new functional stimuli-responsive supramolecular assemblies. Here, we present three isomeric supramolecular coordination complexes consisting of a Pd2L4 stoichiometry. As shown by NMR, CD and X-ray studies, as well as DFT calculations, these complexes form cage-like structures by chiral self-sorting. Photochromic ligands derived from first generation molecular motors enable light-driven interconversion between the three isomers. Two of the isomers were able to form host–guest complexes opening up new prospects toward stimuli-controlled substrate binding and release.

scholarly journals Doubling the Carbonate-Binding Capacity of Nanojars by the Formation of Expanded Nanojars

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3083
Author(s):  
Wisam A. Al Isawi ◽  
Gellert Mezei
Keyword(s):  
Co2 Fixation ◽  
Binding Capacity ◽  
Coordination Complexes ◽  
Anion Binding ◽  
Ionization Mass ◽  
X Ray ◽  
Carbonate Ion ◽  
Carbonate Ions ◽  
Supramolecular Coordination ◽  
Hydration Energies

Anion binding and extraction from solutions is currently a dynamic research topic in the field of supramolecular chemistry. A particularly challenging task is the extraction of anions with large hydration energies, such as the carbonate ion. Carbonate-binding complexes are also receiving increased interest due to their relevance to atmospheric CO2 fixation. Nanojars are a class of self-assembled, supramolecular coordination complexes that have been shown to bind highly hydrophilic anions and to extract even the most hydrophilic ones, including carbonate, from water into aliphatic solvents. Here we present an expanded nanojar that is able to bind two carbonate ions, thus doubling the previously reported carbonate-binding capacity of nanojars. The new nanojar is characterized by detailed single-crystal X-ray crystallographic studies in the solid state and electrospray ionization mass spectrometric (including tandem MS/MS) studies in solution.

scholarly journals Pt(II)-Coordinated Tricomponent Supramolecular Assemblies of Tetrapyridyl Porphyrin and Dicarboxylate Ligands: Are They 2D Bow Ties or 3D Prisms?

2021 ◽  
Author(s):  
Paola Benavides ◽  
Monica A. Gordillo ◽  
Ashok Yadav ◽  
M. Andrey Joaqui-Joaqui ◽  
Sourav Saha
Keyword(s):  
Self Assembly ◽  
Nmr Spectra ◽  
Structural Complexity ◽  
2D Nmr ◽  
Coordination Complexes ◽  
The Self ◽  
Computational Studies ◽  
X Ray ◽  
Supramolecular Coordination ◽  
Bow Tie

Thermodynamically favored heteroleptic coordination of one aza- and another oxo-coordinating ligand with Pt(II) ions yield tricomponent supramolecular coordination complexes (SCCs) that have much greater structural complexity and functional diversity than the traditional bicomponent SCCs containing only one of the ligands. Herein, we demonstrate that heteroleptic coordination of tetrapyridyl porphyrins (M¢TPP, M¢ = Zn or H2) and various dicarboxylate ligands (XDC) having different lengths and rigidity with cis- (Et3P)2PtII corners actually yields bow tie (⋈)-shaped tricomponent [{cis-(Et3P)2Pt}4(M¢TPP)(XDC)2] 4+ complexes featuring a M¢TPP core and two parallel XDC linkers held together by four heteroligated PtII(N,O) corners. Although previous reports have claimed that the self-assembly of these three components produced tetragonal prisms having two cofacial M¢TPP planes connected by four XDC linkers via eight PtII(N,O) corners, our extensive 1 H, 31P, and 2D NMR, ESI-MS, X-ray crystallographic, and computational studies unequivocally demonstrated that in reality, no such prism was formed because instead of connecting two cofacial M¢TPP ligands, the XDC linkers actually bridged two adjacent pyridyl termini of an M¢TPP ligand via shared PtII(N,O) corners, forming bow tie complexes. In addition to direct crystallographic evidence, the NMR spectra of these complexes revealed that the M¢TPP ligands contained two distinct pyrrole protons (4 each)—those located inside the triangles were shielded by and coupled to adjacent XDC linkers, whereas the exposed ones were not—an unmistakable sign of their bow tie structures. Thus, this work not only unveiled novel bow tie-shaped coordination complexes, but also accurately defined the actual structures and compositions of M¢TPP-based tricomponent SCCs.

scholarly journals Pt(II)-Coordinated Tricomponent Self-Assemblies of Tetrapyridyl Porphyrin and Dicarboxylate Ligands: Are They 3D Prisms or 2D Bow Ties?

2021 ◽  
Author(s):  
Paola Benavides ◽  
Monica A. Gordillo ◽  
Ashok Yadav ◽  
M. Andrey Joaqui-Joaqui ◽  
Sourav Saha
Keyword(s):  
Structural Complexity ◽  
2D Nmr ◽  
Coordination Complexes ◽  
Computational Studies ◽  
X Ray ◽  
X Ray Crystallography ◽  
Supramolecular Coordination ◽  
Ct Complex ◽  
A Charge ◽  
Bow Tie

Thermodynamically favored heteroleptic coordination of Pt(II) ions with one aza- and another oxo-coordinating ligand yield tricomponent supramolecular coordination complexes (SCCs), which possess much greater structural complexity and functional diversity than traditional bicomponent SCCs containing only one of the ligands. Through X-ray crystallography, 1H, 31P, and 2D NMR spectroscopies, mass spectrometry, and computational studies, herein, we demonstrated that heteroleptic coordination of tetrapyridyl porphyrins (MTPP, M = Zn or H2) and various dicarboxylate ligands (XDC) having different lengths and rigidity with cis-(Et3P)2PtII corners yielded bow-tie (⋈)-shaped tricomponent [{cis-(Et3P)2Pt}4(MTPP)(XDC)2]4+ complexes featuring a MTPP core and two parallel XDC linkers held together by four heteroligated PtII(N,O) corners and ruled out the MTPP-based tetragonal prism formation. Irrespective of the rigidity and length of the XDC linkers within a certain range (~7–11 Å), they intramolecularly bridged two adjacent pyridyl tips of an MTPP ligand via PtII(N,O) corners, which led to the formation of bow-tie complexes instead of prisms. This happened because the angles of projection between the adjacent pyridyl rings of MTPP cores adapted to accommodate the bridging XDC linkers having different lengths, and the bow-tie formation was entropically favored over tetragonal prisms. This work not only unveiled novel bow-tie-shaped coordination complexes, but also accurately defined the actual structures and compositions of MTPP-based tricomponent SCCs. Furthermore, a representative bow-tie complex containing an electron-rich ZnTPP core selectively formed a charge-transfer (CT) complex with highly electron deficient 1,4,5,8,9,12-hexaazatriphenylene-2,3,6,7,10,11-heaxacarbonitrile (HATHCN) but not with π-donors like pyrene.

scholarly journals Pt(II)-Coordinated Tricomponent Supramolecular Assemblies of Tetrapyridyl Porphyrin and Dicarboxylate Ligands: Are They 2D Bow Ties or 3D Prisms?

2021 ◽  
Author(s):  
Paola Benavides ◽  
Monica A. Gordillo ◽  
Ashok Yadav ◽  
M. Andrey Joaqui-Joaqui ◽  
Sourav Saha
Keyword(s):  
Self Assembly ◽  
Nmr Spectra ◽  
Structural Complexity ◽  
2D Nmr ◽  
Coordination Complexes ◽  
The Self ◽  
Computational Studies ◽  
X Ray ◽  
Supramolecular Coordination ◽  
Bow Tie

Thermodynamically favored heteroleptic coordination of one aza- and another oxo-coordinating ligand with Pt(II) ions yield tricomponent supramolecular coordination complexes (SCCs) that have much greater structural complexity and functional diversity than the traditional bicomponent SCCs containing only one of the ligands. Herein, we demonstrate that heteroleptic coordination of tetrapyridyl porphyrins (M¢TPP, M¢ = Zn or H2) and various dicarboxylate ligands (XDC) having different lengths and rigidity with cis- (Et3P)2PtII corners actually yields bow tie (⋈)-shaped tricomponent [{cis-(Et3P)2Pt}4(M¢TPP)(XDC)2] 4+ complexes featuring a M¢TPP core and two parallel XDC linkers held together by four heteroligated PtII(N,O) corners. Although previous reports have claimed that the self-assembly of these three components produced tetragonal prisms having two cofacial M¢TPP planes connected by four XDC linkers via eight PtII(N,O) corners, our extensive 1 H, 31P, and 2D NMR, ESI-MS, X-ray crystallographic, and computational studies unequivocally demonstrated that in reality, no such prism was formed because instead of connecting two cofacial M¢TPP ligands, the XDC linkers actually bridged two adjacent pyridyl termini of an M¢TPP ligand via shared PtII(N,O) corners, forming bow tie complexes. In addition to direct crystallographic evidence, the NMR spectra of these complexes revealed that the M¢TPP ligands contained two distinct pyrrole protons (4 each)—those located inside the triangles were shielded by and coupled to adjacent XDC linkers, whereas the exposed ones were not—an unmistakable sign of their bow tie structures. Thus, this work not only unveiled novel bow tie-shaped coordination complexes, but also accurately defined the actual structures and compositions of M¢TPP-based tricomponent SCCs.

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>

Copper–oxygen Dynamics in Tyrosinase

2019 ◽  
Author(s):  
Nobutaka Fujieda ◽  
Sachiko Yanagisawa ◽  
Minoru Kubo ◽  
Genji Kurisu ◽  
Shinobu Itoh
Keyword(s):  
Catalytic Mechanism ◽  
Substrate Binding ◽  
Active Form ◽  
Copper Ion ◽  
Atomic Resolution ◽  
Oxygen Species ◽  
X Ray ◽  
Oxygen Dynamics ◽  
Insight Into ◽  
Copper Centre

To unveil the activation of dioxygen on the copper centre (Cu<sub>2</sub>O<sub>2</sub>core) of tyrosinase, we performed X-ray crystallograpy with active-form tyrosinase at near atomic resolution. This study provided a novel insight into the catalytic mechanism of the tyrosinase, including the rearrangement of copper-oxygen species as well as the intramolecular migration of copper ion induced by substrate-binding.<br>

The Concerted Nature of the Enzymatic Cyclization of Rings A-D of Squalene to Hopene

2008 ◽  
Vol 73 (6-7) ◽  
pp. 786-794 ◽  
Author(s):  
B. Andes Hess ◽  
Lidia Smentek
Keyword(s):  
Dft Calculations ◽  
Conformational Analysis ◽  
X Ray

A conformational analysis of squalene encapsulated in squalene-hopene cyclase has been performed based on Schulz's X-ray structure and our DFT calculations. Based on this analysis it is concluded that the formation of rings A-D in the cyclization of squalene are likely to be a concerted but highly asynchronous reaction.

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