Azide Decomposition as a Pathway to Intramolecularly Upper Rim-Bridged Calix[4]arenes

Synthesis ◽  
2021 ◽  
Author(s):  
Martin Tlusty ◽  
Vaclav Eigner ◽  
Pavel Lhotak
Keyword(s):  
Thermal Decomposition ◽  
Single Atom ◽  
Indole Derivatives ◽  
Nmr Titration ◽  
Bridge Function ◽  
Inherently Chiral ◽  
Upper Rim

Proximally single-atom bridged calix[4]arenes possess a rigidified cavity and, thus, unusual complexation properties. Here, we report on the synthesis of the first such heteroatom-bridged compound: amine-bridged calix[4]arene. This compound, prepared by thermal decomposition of 4-azidocalix[4]arene, was obtained alongside very interesting rearranged inherently chiral 10H-azepino[1,2-a]indole derivatives. NMR titration confirmed the suitability of amine cavity for the complexation of methylamonnium cations; moreover, the -NH- bridge function enables its further derivatization.

Regioselective formation of the quinazoline moiety on the upper rim of calix[4]arene as a route to inherently chiral systems

2020 ◽  
Vol 44 (16) ◽  
pp. 6490-6500
Author(s):  
M. Tlustý ◽  
H. Dvořáková ◽  
J. Čejka ◽  
M. Kohout ◽  
P. Lhoták
Keyword(s):  
Inherently Chiral ◽  
Chiral Systems ◽  
Upper Rim ◽  
Inherently Chiral Calixarenes

N-acyl aminocalix[4]arenes were cyclized with nitriles to afford the expected quinazolines only in the case of para-substituted series. This strategy represents a new route to inherently chiral calixarenes potentially useful as fluorescent receptors.

25‐Propyloxy‐26,27‐dibenzoyloxy‐calix[4]arene as Precursor of Inherently Chiral Calixarenes with AB and ABC Substitution Patterns at the Upper Rim

2021 ◽  
Author(s):  
Oleksandr O. Trybrat ◽  
Oleksandr A. Yesypenko ◽  
Svitlana V. Shishkina ◽  
Eduard B. Rusanov ◽  
Yevgen A. Karpichev ◽  
...  
Keyword(s):  
Inherently Chiral ◽  
Upper Rim ◽  
Inherently Chiral Calixarenes

Ketone transformation as a pathway to inherently chiral rigidified calix[4]arenes

2020 ◽  
Vol 56 (84) ◽  
pp. 12773-12776
Author(s):  
Martin Tlustý ◽  
Dita Spálovská ◽  
Michal Kohout ◽  
Václav Eigner ◽  
Pavel Lhoták
Keyword(s):  
Carbonyl Group ◽  
Group Formation ◽  
Inherently Chiral ◽  
Novel Strategy ◽  
Upper Rim

A novel strategy for bridging the upper rim of calix[4]arenes consisting in carbonyl group formation and subsequent “extension” into a two-atom bridge is presented.

scholarly journals Synthesis of upper rim-double-bridged calix[4]arenes bearing seven membered rings and related compounds

RSC Advances ◽  
2019 ◽  
Vol 9 (38) ◽  
pp. 22017-22030 ◽  
Author(s):  
M. Tlustý ◽  
V. Eigner ◽  
M. Babor ◽  
M. Kohout ◽  
P. Lhoták
Keyword(s):  
Chiral Recognition ◽  
Inherently Chiral ◽  
Upper Rim ◽  
Related Compounds

Calix[4]arenes bearing one or two bridges on the upper rim were prepared as novel inherently chiral derivatives potentially capable of chiral recognition.

scholarly journals Inherently chiral cone-calix[4]arenes via a subsequent upper rim ring-closing/opening methodology

2018 ◽  
Vol 16 (39) ◽  
pp. 7255-7264
Author(s):  
José Augusto Berrocal ◽  
Matthew B. Baker ◽  
Laura Baldini ◽  
Alessandro Casnati ◽  
Stefano Di Stefano
Keyword(s):  
Inherently Chiral ◽  
Upper Rim

The introduction of a lactone moiety spanning the distal positions in the upper rim of cone-calix[4]arenes allows the preparation of inherently chiral derivatives.

Inherently Chiral Upper-Rim-Bridged Calix[4]arenes Possessing a Seven Membered Ring

2017 ◽  
Vol 19 (11) ◽  
pp. 2933-2936 ◽  
Author(s):  
Martin Tlustý ◽  
Petr Slavík ◽  
Michal Kohout ◽  
Václav Eigner ◽  
Pavel Lhoták
Keyword(s):  
Membered Ring ◽  
Inherently Chiral ◽  
Upper Rim

scholarly journals Fluorinated Tetraphosphonate Cavitands

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2670 ◽  
Author(s):  
Alessandro Pedrini ◽  
Federico Bertani ◽  
Enrico Dalcanale
Keyword(s):  
Methyl Ester ◽  
Fluorine Atom ◽  
19F Nmr ◽  
Para Position ◽  
Ester Hydrochloride ◽  
Methyl Ester Hydrochloride ◽  
Phenyl Substituent ◽  
Nmr Titration ◽  
Downfield Shift ◽  
Upper Rim

Two synthetic protocols for the introduction of fluorine atoms into resorcinarene-based cavitands, at the lower and upper rim, respectively, are reported. Cavitand 1, bearing four fluorocarbon tails, and cavitand 2, which presents a fluorine atom on the para position of a diester phosphonate phenyl substituent, were synthesized and their complexation abilities toward the model guest sarcosine methyl ester hydrochloride were evaluated via NMR titration experiments. The effect of complexation on the 19F NMR resonance of the probe is evident only in the case of cavitand 2, where the inset of the cation-dipole and H-bonding interactions between the P=O bridges and the guest is reflected in a sizable downfield shift of the fluorine probe.

Single Atom Image Contrast in Fixed Beam Dark Field Electron Microscopy

1974 ◽  
Vol 32 ◽  
pp. 366-367
Author(s):  
Wah Chi
Keyword(s):  
Scattering Amplitude ◽  
Present Report ◽  
Dark Field ◽  
Image Contrast ◽  
Single Atom ◽  
Optical Theorem ◽  
Hartree Fock ◽  
Heavy Atoms ◽  
Beam Stop ◽  
Fixed Beam

Resolution and contrast are the important factors to determine the feasibility of imaging single heavy atoms on a thin substrate in an electron microscope. The present report compares the atom image characteristics in different modes of fixed beam dark field microscopy including the ideal beam stop (IBS), a wire beam stop (WBS), tilted illumination (Tl) and a displaced aperture (DA). Image contrast between one Hg and a column of linearly aligned carbon atoms (representing the substrate), are also discussed. The assumptions in the present calculations are perfectly coherent illumination, atom object is represented by spherically symmetric potential derived from Relativistic Hartree Fock Slater wave functions, phase grating approximation is used to evaluate the complex scattering amplitude, inelastic scattering is ignored, phase distortion is solely due to defocus and spherical abberation, and total elastic scattering cross section is evaluated by the Optical Theorem. The atom image intensities are presented in a Z-modulation display, and the details of calculation are described elsewhere.

Applications of Photoelectron Microscopy

1976 ◽  
Vol 34 ◽  
pp. 506-507
Author(s):  
William J. Baxter
Keyword(s):  
Electron Microscopy ◽  
Thermal Decomposition ◽  
Chemical Composition ◽  
Ultraviolet Radiation ◽  
Thin Layer ◽  
Edge Effects ◽  
Electron Optics ◽  
Surface Layers ◽  
Crystalline Orientation ◽  
Fluorescent Screen

In this form of electron microscopy, photoelectrons emitted from a metal by ultraviolet radiation are accelerated and imaged onto a fluorescent screen by conventional electron optics. image contrast is determined by spatial variations in the intensity of the photoemission. The dominant source of contrast is due to changes in the photoelectric work function, between surfaces of different crystalline orientation, or different chemical composition. Topographical variations produce a relatively weak contrast due to shadowing and edge effects.Since the photoelectrons originate from the surface layers (e.g. ∼5-10 nm for metals), photoelectron microscopy is surface sensitive. Thus to see the microstructure of a metal the thin layer (∼3 nm) of surface oxide must be removed, either by ion bombardment or by thermal decomposition in the vacuum of the microscope.

Preparation and characterisation of vanadium pentoxide supported rhodium catalyst

1988 ◽  
Vol 46 ◽  
pp. 946-947
Author(s):  
A. Legrouri
Keyword(s):  
Aqueous Solution ◽  
Thermal Decomposition ◽  
Physicochemical Properties ◽  
Surface Area ◽  
Vanadium Pentoxide ◽  
High Purity ◽  
Gas Adsorption ◽  
Rhodium Catalyst ◽  
Optical Methods ◽  
Reducible Oxides

The industrial importance of metal catalysts supported on reducible oxides has stimulated considerable interest during the last few years. This presentation reports on the study of the physicochemical properties of metallic rhodium supported on vanadium pentoxide (Rh/V2O5). Electron optical methods, in conjunction with other techniques, were used to characterise the catalyst before its use in the hydrogenolysis of butane; a reaction for which Rh metal is known to be among the most active catalysts.V2O5 powder was prepared by thermal decomposition of high purity ammonium metavanadate in air at 400 °C for 2 hours. Previous studies of the microstructure of this compound, by HREM, SEM and gas adsorption, showed it to be non— porous with a very low surface area of 6m2/g3. The metal loading of the catalyst used was lwt%Rh on V2Q5. It was prepared by wet impregnating the support with an aqueous solution of RhCI3.3H2O.

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