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1. Photodegradation of hydroxyfluorenes in ice and water: A comparison of kinetics, effects of water constituents, and phototransformation by-products

Author:
Linke Ge; Shengkai Cao; Crispin Halsall; Junfeng Niu; Dongxiao Bai; Guangkai He; Peng Zhang; Hongrui Ma
Source:
Journal of environmental sciences (China) 2023 v.124 pp. 139-145
ISSN:
1001-0742
Subject:
isomers,   etc   ; aqueous solutions; cold; fluorenes; humic acids; hydroxylation; ice; photolysis; tandem mass spectrometry; China;     Show all 10 Subjects
Abstract:
... The photochemical behavior of organic pollutants in ice is poorly studied in comparison to aqueous photochemistry. Here we report a detailed comparison of ice and aqueous photodegradation of two representative OH-PAHs, 2-hydroxyfluorene (2-OHFL) and 9-hydroxyfluorene (9-OHFL), which are newly recognized contaminants in the wider environment including colder regions. Interestingly, their photodegra ...
DOI:
10.1016/j.jes.2021.11.002

2. Lactic acid fermentation of osmo-dehydrated onion

Author:
Katarzyna Grzelak-Błaszczyk; Andrzej Czarnecki; Robert Klewicki; Maria Grzegorzewska; Elżbieta Klewicka
Source:
Food chemistry 2023 v.399 pp. 133954
ISSN:
0308-8146
Subject:
isomers,   etc   ; cultivars; food chemistry; fructooligosaccharides; lactic acid; lactic fermentation; onions; osmotic treatment; polyphenols; sodium chloride; sucrose;     Show all 11 Subjects
Abstract:
... The aim of the study was to determine the effect of osmoconcentration in a sucrose and sodium chloride solution on the efficiency of lactic fermentation and the content of polyphenols and oligosaccharides in yellow and red onion varieties: Alonso, Hysky, Hystore, and Red Lady. In most cases, no negative effect of onion dehydration was noted on the growth or number of the bacteria tested. Osmotic d ...
DOI:
10.1016/j.foodchem.2022.133954

3. Bis-periazulene (Cyclohepta[def]fluorene) as a Nonalternant Isomer of Pyrene: Synthesis and Characterization of Its Triaryl Derivatives

Author:
Koki Horii; Ryohei Kishi; Masayoshi Nakano; Daisuke Shiomi; Kazunobu Sato; Takeji Takui; Akihito Konishi; Makoto Yasuda
Source:
Journal of the American Chemical Society 2022 v.144 no.8 pp. 3370-3375
ISSN:
1520-5126
Subject:
isomers,   etc   ; energy; fluorenes;     Show all 3 Subjects
Abstract:
... Bis-periazulene (cyclohepta[def]fluorene), which is an unknown pyrene isomer, was synthesized as kinetically protected forms. Its triaryl derivatives 1c–e exhibited the superimposed electronic structures of peripheral, polarized, and open-shell π-conjugated systems. In contrast to previous theoretical predictions, bis-periazulene derivatives were in the singlet ground state. Changing an aryl group ...
DOI:
10.1021/jacs.2c00476

4. Isomer Selective Thermosalience and Luminescence Switching in Organic Crystals

Author:
Khalid Naim; Subash Chandra Sahoo; Prakash P. Neelakandan
Source:
ACS applied materials & interfaces 2022 v.14 no.19 pp. 22650-22657
ISSN:
1944-8252
Subject:
isomers,   etc   ; luminescence; spectroscopy;     Show all 3 Subjects
Abstract:
... Organic crystals that respond to external stimuli are interesting for the design of smart materials. Here, we show that molecular engineering can transform simple naphthalidenimine–boron complexes─known for their exciting photophysical properties─into functional materials that exhibit thermosalience and thermal-luminescence switching. Detailed crystallographic and spectroscopic investigations reve ...
DOI:
10.1021/acsami.2c05053

5. Synthesis and resolution of 2-amino-5-aza[6]helicene

Author:
Esha H. Bhalodi; Krupa N. Patel; Ashutosh V. Bedekar
Source:
Tetrahedron 2022 v.114 pp. 132761
ISSN:
0040-4020
Subject:
isomers,   etc   ; chromatography; helicenes;     Show all 3 Subjects
Abstract:
... The synthesis of 2-amino-5-aza[6]helicene and its derivatives is reported. The diastereomeric (R)-menthylcarbamate derivative of this aza[6]helicene is prepared and its isomers were physically separated by column chromatography and their optical properties were measured. Optically pure isomer (P)-2-amino-5-aza[6]helicene was generated and its Boc-derivative was prepared. ...
DOI:
10.1016/j.tet.2022.132761

6. Synthesis of the 2,2′:3′,3′':2′',2′'' tetraindole framework of the alkaloid bisindigotin

Author:
Maurycy Prystupa; Tilo Söhnel; Jonathan Sperry
Source:
Tetrahedron letters 2022 v.106 pp. 154082
ISSN:
0040-4039
Subject:
positional isomers,   etc   ; alkaloids; dimerization; oxidation;     Show all 4 Subjects
Abstract:
... Previous efforts towards the alkaloid bisindigotin using 3-hydroxyindole based precursors was dominated by rearrangement chemistry that destroys the desired tetraindole framework of the natural product. Herein, we report a synthesis of the 2,2′:3′,3′':2′',2′''-tetraindole core of the putative bisindigotin structure through a strategic ordering of oxidative dimerization, reduction and dehydration e ...
DOI:
10.1016/j.tetlet.2022.154082

7. Identification of side-reaction products generated during the ammonia-catalyzed release of N-glycans

Author:
Chia Yen Liew; Jien-Lian Chen; Shang-Ting Tsai; Chi-Kung Ni
Source:
Carbohydrate research 2022 v.522 pp. 108686
ISSN:
0008-6215
Subject:
isomers,   etc   ; N-acetylglucosamine; glycosylation; research;     Show all 4 Subjects
Abstract:
... N-linked glycosylation is one of the most important post translational modification of proteins. Various analytical techniques are used for the structural identification of the N-glycans released from proteins through various enzymatic and chemical methods. Although very few side-reaction products are generated during the enzymatic release of N-glycans, this method is expensive and suitable only f ...
DOI:
10.1016/j.carres.2022.108686

8. Selective Axial-to-Equatorial Epimerization of Carbohydrates

Author:
Hayden M. Carder; Yong Wang; Alison E. Wendlandt
Source:
Journal of the American Chemical Society 2022 v.144 no.26 pp. 11870-11877
ISSN:
1520-5126
Subject:
isomers,   etc   ; alcohols; isomerization; polysaccharides; sugars;     Show all 5 Subjects
Abstract:
... Radical-mediated transformations have emerged as powerful methods for the synthesis of rare and unnatural branched, deoxygenated, and isomeric sugars. Here, we describe a radical-mediated axial-to-equatorial alcohol epimerization method to transform abundant glycans into rare isomers. The method delivers highly predictable and selective reaction outcomes that are complementary to other sugar isome ...
DOI:
10.1021/jacs.2c04743

9. Unveiling two antiaromatic s-indacenodicarbazole isomers with tunable paratropicity

Author:
Hemonta Kumar Saha; Dibyendu Mallick; Soumyajit Das
Source:
Chemical communications 2022 v.58 no.61 pp. 8492-8495
ISSN:
1364-548X
Subject:
isomers,   etc   ; energy; ultraviolet-visible spectroscopy;     Show all 3 Subjects
Abstract:
... Linear and curved antiaromatic s-indacenodicarbazole isomers were synthesized and characterized to show the tunable paratropicity of s-indacene, as analyzed by NICS(1)zz and ACID (ring-current) calculations. The curved isomer showed a greater degree of antiaromaticity than the linear isomer, as predicted by the Glidewell–Lloyd rule. This degree of antiaromaticity was further validated by the red-s ...
DOI:
10.1039/d2cc02318k

10. Controlling Diradical Character of Photogenerated Colored Isomers of Phenoxyl-Imidazolyl Radical Complexes

Author:
Moe Nishijima; Katsuya Mutoh; Rintaro Shimada; Akira Sakamoto; Jiro Abe
Source:
Journal of the American Chemical Society 2022 v.144 no.37 pp. 17186-17197
ISSN:
1520-5126
Subject:
isomers,   etc   ; half life; homolytic cleavage; imidazole;     Show all 4 Subjects
Abstract:
... We propose a rational method for evaluating the diradical character of the photochromic phenoxyl-imidazolyl radical complex (PIC) derivatives based on their radical–radical coupling reaction rates. PIC consists of an imidazole ring, a phenoxyl ring, and a bridging unit that structurally connects them. The C–N bond formed between the imidazole and phenoxyl rings can be dissociated photochemically i ...
DOI:
10.1021/jacs.2c07562

11. Synthesis of α-Tropolones through Autoxidation of Dioxole-Fused Cycloheptatrienes

Author:
Alex J. Berkowitz; Ryan P. Murelli
Source:
Journal of organic chemistry 2022 v.87 no.7 pp. 4499-4507
ISSN:
1520-6904
Subject:
isomers,   etc   ; air; autoxidation; chromatography; organic chemistry;     Show all 5 Subjects
Abstract:
... Herein, we describe the formation of tropolones through the autoxidation of Büchner reaction-derived cycloheptatrienes. The reaction is exceptionally simple procedurally, as it involves blowing a stream of compressed air over the cycloheptatriene, and the products can be obtained without any need for chromatography. The chemistry works specifically on dioxolane-fused systems or close variants, an ...
DOI:
10.1021/acs.joc.1c02713

12. Full liberation of 2-Aminopurine with nucleases digestion for highly sensitive biosensing

Author:
Xianming Li; Hang Yang; Jialun He; Bin Yang; Yi Zhao; Peng Wu
Source:
Biosensors & bioelectronics 2022 v.196 pp. 113721
ISSN:
0956-5663
Subject:
isomers,   etc   ; adenine; biosensors; digestion; fluorescence; nucleases;     Show all 6 Subjects
Abstract:
... 2-Aminopurine (2-AP), a fluorescent isomer of adenine, is a popular fluorescent tag for DNA-based biosensors. The fluorescence of 2-AP is highly dependent on its microenvironment, i.e., almost non-fluorescent and merely fluorescent in dsDNA and ssDNA, respectively, but can be greatly brightened as mononucleotide. In most 2-AP-based biosensors, DNA transformation from dsDNA to ssDNA was employed, w ...
DOI:
10.1016/j.bios.2021.113721

13. Fundamental Study of the Optical and Vibrational Properties of Fx-AZB@MOF systems as Functions of Dye Substitution and the Loading Amount

Author:
Markus Rödl; Alen Reka; Marko Panic; Alexander Fischereder; Marco Oberlechner; Thomas Mairegger; Holger Kopacka; Hubert Huppertz; Thomas S. Hofer; Heidi A. Schwartz
Source:
Langmuir 2022 v.38 no.14 pp. 4295-4309
ISSN:
1520-5827
Subject:
cis-trans isomers,   etc   ; dyes; molecular dynamics;     Show all 3 Subjects
Abstract:
... Controlling the switching efficiency of photoactive hybrid systems is an obligatory key prerequisite for systematically improving the design of functional materials. By modulating the degree of fluorination and the amount being embedded into porous hosts, the E/Z ratios of fluorinated azobenzenes were adjusted as both functions of substitution and the degree of loading. Octafluoroazobenzene (F8-AZ ...
DOI:
10.1021/acs.langmuir.1c03482

14. Total Synthesis of (−)-Antroalbocin A Enabled by a Strain Release-Controlled Photochemical 1,3-Acyl Shift

Author:
Björn Siekmeyer; Dennis Lübken; Kevin Bajerke; Bastian Bernhardt; Peter R. Schreiner; Markus Kalesse
Source:
Organic letters 2022 v.24 no.31 pp. 5812-5816
ISSN:
1523-7052
Subject:
isomers,   etc   ; catalytic activity; enantioselectivity; photochemistry; sesquiterpenoids;     Show all 5 Subjects
Abstract:
... The first bioinspired, enantioselective, and protecting group free total synthesis of the antibacterial sesquiterpenoid (−)-antroalbocin A (1) has been achieved in 12 steps (5.4% overall yield) from dimedone. An organocatalytic Robinson annulation gave rapid access to the tricyclic enone (19) as starting material for the photochemical domino process of deconjugation and sigmatropic 1,3-acyl shift. ...
DOI:
10.1021/acs.orglett.2c02347

15. Diastereoselective access to substituted oxetanes via hydrosilylation–iodocyclisation of homopropargylic alcohols

Author:
Dean D. Roberts; Mark G. McLaughlin
Source:
Chemical communications 2022 v.58 no.60 pp. 8376-8379
ISSN:
1364-548X
Subject:
positional isomers,   etc   ; diastereoselective synthesis; diastereoselectivity; silane;     Show all 4 Subjects
Abstract:
... The regio and stereoselective hydrosilylation of a variety of homopropargylic alcohols and their derivatives is described. The reaction is tolerant to a variety of sterically and electronically varied substrates, affording only the E-vinyl silane as a sole regioisomer. The application of the resultant vinyl silanes towards the diastereoselective synthesis of tetrasubstituted oxetanes is demonstrat ...
DOI:
10.1039/d2cc03339a

16. Synthesis of N-Vinyl Cinnamaldehyde Nitrones through Atropisomeric Quinoxaline-Derived N,N,O-Ligand-Promoted Chan-Lam Reaction

Author:
Hao Chen; Cui Wei; Guang-Li Pang; Cui Liang; Dong-Liang Mo; Xiao-Pan Ma
Source:
Organic letters 2022 v.24 no.32 pp. 6013-6017
ISSN:
1523-7052
Subject:
cis-trans isomers,   etc   ; indoles; iodination; oxidation;     Show all 4 Subjects
Abstract:
... A type of quinoxaline-derived tridentate N,N,O-ligand was synthesized in good to excellent yields over three steps through iodination of 2-aryl indoles, sequential Kornblum-type oxidation with DMSO, and capture by 1,2-diaminobenzenes. The prepared atropisomeric N,N,O-ligand was successfully applied in the synthesis of N-vinyl cinnamaldehyde nitrones as only Z-isomers in good yields through the Cha ...
DOI:
10.1021/acs.orglett.2c02288

17. An experimental investigation into the kinetics and mechanism of the aza-Michael additions of dimethyl itaconate

Author:
Daniel M. Day; Thomas J. Farmer; James Sherwood; James H. Clark
Source:
Tetrahedron 2022 v.121 pp. 132921
ISSN:
0040-4020
Subject:
positional isomers,   etc   ; acidity; catalysts; isomerization; solvents;     Show all 5 Subjects
Abstract:
... The aza-Michael addition is a versatile reaction for the modification of α,β-unsaturated carbonyl compounds with amines. The reactivity of dimethyl itaconate as a bio-based Michael acceptor is explored in this work. Through its reactions with piperidine and dibutylamine, it was found that the order of reaction can be changed by the choice of catalyst, solvent, or the concentration of the amine rea ...
DOI:
10.1016/j.tet.2022.132921

18. Controlling diffusion resistance, selectivity and deactivation of ZSM-5 catalysts by crystal thickness and defects

Author:
Jonas Hedlund; Ming Zhou; Abrar Faisal; Olov G.W. Öhrman; Valeria Finelli; Matteo Signorile; Valentina Crocellà; Mattias Grahn
Source:
Journal of catalysis 2022 v.410 pp. 320-332
ISSN:
0021-9517
Subject:
isomers,   etc   ; carbon; catalytic activity; gasoline; methanol; zeolites;     Show all 6 Subjects
Abstract:
... A systematic investigation of two sets of defect free and defective ZSM-5 crystals with controlled thickness (T) between 30 and 400 nm and of their performances in methanol conversion was reported for the first time in the present work. The defect free ZSM-5 crystals with a thickness of 35 nm are by far the smallest ever reported and displayed superior activity, stability and selectivity to slower ...
DOI:
10.1016/j.jcat.2022.04.013

19. Impacts of Solvent and Alkyl Chain Length on the Lifetime of Singlet Cyclopentane-1,3-diyl Diradicaloids with π-Single Bonding

Author:
Qian Liu; Zhe Wang; Manabu Abe
Source:
Journal of organic chemistry 2022 v.87 no.3 pp. 1858-1866
ISSN:
1520-6904
Subject:
isomers,   etc   ; homolytic cleavage; isomerization; organic chemistry; viscosity;     Show all 5 Subjects
Abstract:
... The singlet 2,2-dialkoxycyclopentane-1,3-diyl diradicaloids are not only the important key intermediates in the process of bond homolysis but are also attracting attention as π-single bonding compounds. In the present study, the effects of solvent viscosity η (0.24–125.4 mPa s) and polarity π* (−0.11 to 1.00 kcal mol–¹) on the reactivity of localized singlet diradicaloids were thoroughly investiga ...
DOI:
10.1021/acs.joc.1c02895

20. Synthesis of the two isomers of heteroleptic Rh₁₂L₆L′₆ metal–organic polyhedra by screening of complementary linkers

Author:
Anna Broto-Ribas; María Susana Gutiérrez; Inhar Imaz; Arnau Carné-Sánchez; Felipe Gándara; Judith Juanhuix; Daniel Maspoch
Source:
Chemical communications 2022 v.58 no.75 pp. 10480-10483
ISSN:
1364-548X
Subject:
isomers,   etc   ; acetates; dicarboxylic acids; porous media; rhodium;     Show all 5 Subjects
Abstract:
... We have synthesised and characterised the two possible isomers of heteroleptic trigonal antiprismatic M₁₂L₆L′₆ MOPs by screening reactions of rhodium acetate with different pairs of complementary dicarboxylate linkers. The resulting 12 new MOPs (eight of isomer A + four of isomer B) are microporous in the solid state, exhibiting Brunauer–Emmett–Teller (BET) surface areas as high as 770 m² g⁻¹. ...
DOI:
10.1039/d2cc03220a