Bis-palladium(II) complex of doubly N-confused octaphyrin(1.1.1.1.1.1.1.1): Möbius aromaticity and chiroptical properties

2020 ◽  
Vol 24 (01n03) ◽  
pp. 416-423
Author(s):  
Biju Basumatary ◽  
Koki Mitsuno ◽  
Masatoshi Ishida ◽  
Hiroyuki Furuta
Keyword(s):  
Near Infrared ◽  
Chemical Shifts ◽  
Conformational Stability ◽  
Cyclic Voltammogram ◽  
Resonance Contribution ◽  
H Nmr ◽  
Aromatic Character ◽  
Nucleus Independent Chemical Shift ◽  
Electronic Delocalization ◽  
Absorption Features

A novel bis-palladium(II) complex of doubly N-confused octaphyrin (Pd[Formula: see text]-2) adopting a Möbius-twisted topological structure was synthesized and characterized. Due to the effective 36[Formula: see text]-electronic delocalization over the Möbius-twisted octaphyrin scaffold, characteristic Soret and Q-like absorption features were observed in the near-infrared (NIR) region. However, the complex Pd[Formula: see text]-2 exhibited weak aromatic character attributed to the distinct cross-conjugated resonance contribution as inferred from the 1H NMR chemical shifts as well as theoretical assessments ([Formula: see text] nucleus-independent chemical shift (NICS)). Since the bis-palladium(II) complexation of doubly N-confused octaphyrin 2 imparted significant conformational stability, topologically chiral enantiomers of Pd[Formula: see text]-2 were successfully separated as ([Formula: see text]- and ([Formula: see text]-twisted forms. The resulting isomers revealed relatively large circular dichroism (CD) responses with an absorption anisotropy factor of [Formula: see text] [Formula: see text] 0.009 in the NIR region ([Formula: see text] 823 nm). In addition, the cyclic voltammogram of Pd[Formula: see text]-2 revealed redox-rich properties due to its large [Formula: see text]-conjugated system.

scholarly journals Nucleus-independent chemical shift profiles along the intrinsic distortion path for Jahn-Teller active molecules. Study on cyclopentadienyl radical and cobaltocene

2015 ◽  
Vol 80 (7) ◽  
pp. 877-888 ◽  
Author(s):  
Ljubica Andjelkovic ◽  
Marko Peric ◽  
Matija Zlatar ◽  
Maja Gruden-Pavlovic
Keyword(s):  
Density Functional ◽  
Chemical Shifts ◽  
High Symmetry ◽  
Functional Theory ◽  
Aromatic Character ◽  
Nucleus Independent Chemical Shift ◽  
Jahn Teller ◽  
Cyclopentadienyl Radical ◽  
Cyclopentadienyl Anion ◽  
Low Symmetry

The aromatic/antiaromatic behavior of the cyclopentadienyl anion (Cp-), bis(?5-cyclopentadienyl)iron(II) (Fe(Cp)2), as well as of the Jahn-Teller (JT) active cyclopentadienyl radical (Cp?) and bis(?5-cyclopentadienyl)cobalt(II) (Co(Cp)2) has been investigated using Density Functional Theory (DFT) calculations of the Nuclear Independent Chemical Shifts (NICS). According to the NICS values, pentagon ring in Fe(Cp)2 is more aromatic than isolated Cp-. The NICS parameters have been scanned along the Intrinsic Distortion Path (IDP) for Cp? and Co(Cp)2 showing antiaromaticity, which decreases with increasing deviation from high symmetry D5h to low symmetry (LS) C2v. Changes in the NICS values along the IDP revealed that Co(Cp)2 in the LS nuclear arrangement has aromatic character, in contrast to the case of Cp?

scholarly journals 13C and 1H NMR Spectra of Synthetic (25R)-5α-Spirostanes

1999 ◽  
Vol 23 (1) ◽  
pp. 48-49
Author(s):  
Martín A. Iglesias Arteaga ◽  
Carlos S. Pérez Martinez ◽  
Roxana Pérez Gil ◽  
Francisco Coll Manchado
Keyword(s):  
1H Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
1H Nmr Spectra ◽  
H Nmr ◽  
C 23 ◽  
Main Effects ◽  
Nmr Signals

The assignment of 13C and 1H NMR signals of synthetic (25 R)-5α-spirostanes is presented; the main effects on chemical shifts due to substitution at C-23 are briefly discussed.

The Strengths of Near‐Infrared Absorption Features Relevant to Interstellar and Planetary Ices

2005 ◽  
Vol 620 (2) ◽  
pp. 1140-1150 ◽  
Author(s):  
P. A. Gerakines ◽  
J. J. Bray ◽  
A. Davis ◽  
C. R. Richey
Keyword(s):  
Infrared Absorption ◽  
Near Infrared ◽  
Absorption Features ◽  
Planetary Ices

Chemical shifts of charge-transfer complexes and Buckingham equation

1990 ◽  
Vol 55 (9) ◽  
pp. 2131-2137
Author(s):  
Mahboob Mohammad ◽  
Ather Yaseen Khan ◽  
Tariq Mahmood ◽  
Ismat Fatima ◽  
Riffat Shaheen ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Nmr Spectra ◽  
Charge Transfer Complex ◽  
Chemical Shifts ◽  
Charge Transfer Complexes ◽  
Aprotic Solvents ◽  
Reaction Field ◽  
H Nmr ◽  
Spherical Cavities ◽  
Dipolar Aprotic Solvents

The 1H NMR spectra of the charge-transfer complex of 1-ethyl-4-methoxycarbonylpyridinium iodide have been recorded in various dipolar aprotic solvents. An attempt is made to interpret the chemical shifts in terms of Buckingham's reaction field equation for spherical cavities. A linear dependence has been found between the δ(2,6) values and the square of dielectric function for a spherical cavity, which confirms the validity of the Buckingham equation for this class of compounds.

THE RELATION OF 15N NMR, 1H NMR CHEMICAL SHIFTS WITH THE ATOMIC NET CHARGE AND MOLECULAR STRUCTURES

1987 ◽  
Vol 3 (06) ◽  
pp. 632-637
Author(s):  
Chen Yuehua ◽  
◽  
Guo Guolin ◽  
Shen Qifeng ◽  
Zhao Yufen ◽  
...  
Keyword(s):  
Chemical Shifts ◽  
Molecular Structures ◽  
Net Charge ◽  
Nmr Chemical Shifts ◽  
H Nmr

scholarly journals Secondary eclipse of the hot Jupiter WASP-121b at 2 μm

2019 ◽  
Vol 625 ◽  
pp. A80 ◽  
Author(s):  
Géza Kovács ◽  
Tamás Kovács
Keyword(s):  
Near Infrared ◽  
Infrared Emission ◽  
Current Data ◽  
Emission Analysis ◽  
Hot Jupiters ◽  
Occultation Data ◽  
The One ◽  
Near Infrared Emission ◽  
Absorption Features ◽  
Hot Jupiter

Ground-based observations of the secondary eclipse in the 2MASS K band are presented for the hot Jupiter WASP-121b. These are the first occultation observations of an extrasolar planet that were carried out with an instrument attached to a 1 m class telescope (the SMARTS 1.3 m). We find a highly significant eclipse depth of (0.228 ± 0.023)%. Together with other planet atmosphere measurements, including the Hubble Space Telescope near-infrared emission spectrum, current data support more involved atmosphere models with species producing emission and absorption features, rather than simple smooth blackbody emission. Analysis of the time difference between the primary and secondary eclipses and the durations of these events yields an eccentricity of e = 0.0207 ± 0.0153, which is consistent with the earlier estimates of low or zero eccentricity, but with a smaller error. Comparing the observed occultation depth in the K band with the one derived under the assumption of zero Bond albedo and full heat redistribution, we find that WASP-121b has a deeper observed occultation depth than predicted. Together with the sample of 31 systems with K-band occultation data, this observation lends further support to the idea of inefficient heat transport between the day and night sides for most of the hot Jupiters.

Aldehyde-Substituted Donor–Acceptor-Type Dithienylethenes as Novel Building Blocks for Photochromic Materials

2018 ◽  
Vol 42 (10) ◽  
pp. 531-534 ◽  
Author(s):  
Yangyang Wang ◽  
Mengna Li ◽  
Yufei Song ◽  
Ming Qin ◽  
Xuehui Li ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Near Infrared ◽  
Building Blocks ◽  
Formyl Group ◽  
Photochromic Properties ◽  
H Nmr ◽  
Donor Acceptor ◽  
Group Functions ◽  
Photochromic Materials ◽  
C Nmr

Two novel donor–π–acceptor-type dithienylethene derivatives, in which the triphenylamine group acts as electron donor and the formyl group functions as electron acceptor, have been developed. Their structures were confirmed by 1H NMR, 13C NMR and HRMS (ESI). Investigation of their photochromic properties indicated that they had good photochromic behaviour and excellent fatigue resistance on irradiation with UV or visible light. DFT calculations further validated these experimental results for photochromic behaviour. Moreover, these compounds can be utilised as versatile building blocks to construct novel near-infrared photochromic materials.

scholarly journals The dwarf planet Makemake as seen by X-Shooter

2020 ◽  
Vol 497 (4) ◽  
pp. 5473-5479
Author(s):  
Alvaro Alvarez-Candal ◽  
Ana Carolina Souza-Feliciano ◽  
Walter Martins-Filho ◽  
Noemí Pinilla-Alonso ◽  
José Luis Ortiz
Keyword(s):  
Infrared Spectrum ◽  
Near Infrared ◽  
Resolving Power ◽  
Large Telescope ◽  
Very Large Telescope ◽  
Absorption Features ◽  
Near Infrared Spectrum

ABSTRACT Makemake is one of the brightest known trans-Neptunian objects, as such, it has been widely observed. Nevertheless, its visibility to near-infrared spectrum has not been completely observed in medium-resolving power, aimed at studying in detail the absorption features of CH4 ice. In this paper, we present the spectrum of Makemake observed with X-Shooter at the Very Large Telescope (Chile). We analyse the detected features, measuring their location and depth. Furthermore, we compare Makemake’s spectrum with that of Eris, obtained with the same instrument and similar setup, to conclude that the bands of the CH4 ice in both objects show similar shifts.

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