- Synthesis and characterization of propeller-shaped mono- to hexacationic quinolinium-substituted benzenes
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Diels-Alder reaction of 2-, 3- and 4-(phenylethynyl)quinolines and tetraphenylcyclopentadienone gave three regioisomeric 2,3,4,5,6-pentaphenyl-1-(quinolin-2-yl, -3-yl, and -4-yl)benzenes. Restricted rotation of the 3-yl and 4-yl substituted derivatives is observed between the central core and the substituents, resulting in propeller-shaped molecules. Likewise, 1,2-diquinolinyl-3,4,5,6-tetraphenylbenzenes with 3-yl,3-yl and 3-yl,4-yl connectivity were prepared. As evidenced by NMR spectroscopy, they form two diasteromers due to their restricted rotation. A cobalt-catalyzed [2 + 2 + 2]-cyclotrimerization of 2-(phenylethynyl)quinoline resulted in the formation of triphenyl-2,4,6- and -3,5,6-tri(quinolin-2-yl)benzenes. The same reaction was applied to 3,3′-ethyne-1,2-diyldiquinoline which formed hexa(quinolin-3-yl)benzene. N-Methylation gave the title compounds. Among those, the hexacationic hexa(N-methylquinolinio-3-yl)benzene is described. Stereochemical aspects are predominantly discussed by means of results of NMR experiments. DFT-calculations on the most stable conformations and the frontier orbital profiles of the hexacation as well as of its neutral precursor have been carried out.
- Batsyts, Sviatoslav,Hübner, Eike G.,Namyslo, Jan C.,Gjikaj, Mimoza,Schmidt, Andreas
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- The Interconnection of Two Positive Charges by Conjugation and Cross-Conjugation in Bis-Quinolinium Ethynyls
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1,4-Diethynylbenzene was used as conjugated all-carbon and rigid spacer between the 2-, 3- and 4-positions of two 1-methylquinolinium rings. Thus, for a systematic study, a series of dicationic salts with 2,2-, 3,3-, 4,4-, 3,2-, and 3,4-interconnections of the two positive charges was prepared, in which all even-numbered substitution patterns are conjugated, and all odd-numbered substitution patterns are cross-conjugated. As a consequence, conjugated/conjugated, cross-conjugated/cross-conjugated, and conjugated/cross-conjugated dications have been prepared. The different combinations result in considerably different charge distributions of the positive charges within the π-electron systems according to the rules of resonance which translate into different DFT-calculated frontier orbital profiles and spectroscopic properties such as 13C NMR chemical shifts, IR and Raman absorptions, and the measured as well as calculated UV/Vis spectra.
- Batsyts, Sviatoslav,Hübner, Eike G.,Namyslo, Jan C.,Schmidt, Andreas
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- Photophysics of monodisperse platinum-acetylide oligomers: Delocalization in the singlet and triplet excited states
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A series of monodisperse Pt-acetylide polymers that contain the [-C≡C-(p-C6H4)-C≡C-(t-Pt(PBu3)2)-]n repeat unit has been prepared for n = 1, 2, 3, 4, 5, and 7. The photophysical properties of the series provide information concerning the relationship between the oligomer length and delocalization in the singlet and triplet excited states of the π-conjugated electron system. The results imply that the singlet excited state is delocalized over approximately 6 repeat units; however, the triplet state is considerably more localized. The triplet energy is almost invariant with oligomer length, but the phosphorescence spectra and triplet nonradiative decay rates indicate that the electron-vibrational coupling in the triplet state decreases with increasing oligomer length. Copyright
- Liu, Yao,Jiang, Shujun,Glusac, Ksenija,Powell, David H.,Anderson, Danielle F.,Schanze, Kirk S.
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- DICARBAMATE INHIBITORS OF NS5A FOR TREATMENT OF HEPATITIS C VIRUS INFECTIONS AND RELATED DISEASES
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Dicarbamate compounds as inhibitors of NS5A, and therapeutic uses and methods of preparation thereof, are disclosed. These compounds, and pharmaceutically acceptable salts, stereoisomers, tautomers, solvates, and prodmgs, and pharmaceutical compositions t
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Page/Page column 38; 39; 40
(2020/11/03)
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- Synthesis and Photochemistry of a New Photolabile Protecting Group for Propargylic Alcohols
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A new and efficient thiochromenone S,S-dioxide-based photolabile protecting group for propargylic alcohols is described. Robust protection reactions were developed through copper (II)-catalyzed substitution of propargylic alcohols. Subsequent photodeprote
- Ma, Chi,Zhang, Youlai,Zhang, Huan,Li, Junru,Nishiyama, Yasuhiro,Tanimoto, Hiroki,Morimoto, Tsumoru,Kakiuchi, Kiyomi
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supporting information
p. 560 - 564
(2017/03/11)
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- Direct Enzymatic Branch-End Extension of Glycocluster-Presented Glycans: An Effective Strategy for Programming Glycan Bioactivity
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The sequence of a glycan and its topology of presentation team up to determine the specificity and selectivity of recognition by saccharide receptors (lectins). Structure–activity analysis would be furthered if the glycan part of a glycocluster could be efficiently elaborated in situ while keeping all other parameters constant. By using a bacterial α2,6-sialyltransferase and a small library of bi- to tetravalent glycoclusters, we illustrate the complete conversion of scaffold-presented lactoside units into two different sialylated ligands based on N-acetyl/glycolyl-neuraminic acid incorporation. We assess the ensuing effect on their bioactivity for a plant toxin, and present an analysis of the noncovalent substrate binding contacts that the added sialic acid moiety makes to the lectin. Enzymatic diversification of a scaffold-presented glycan can thus be brought to completion in situ, offering a versatile perspective for rational glycocluster engineering.
- Bayón, Carlos,He, Ning,Deir-Kaspar, Mario,Blasco, Pilar,André, Sabine,Gabius, Hans-Joachim,Rumbero, ángel,Jiménez-Barbero, Jesús,Fessner, Wolf-Dieter,Hernáiz, María J.
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supporting information
p. 1623 - 1633
(2017/02/10)
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- Crystal Inclusion Formation of a New Type of Dumbbell-Shaped Host Compound Featuring Two Bulky 2,3,4,5-Tetraphenylcyclopenta-2,4-dien-1-ol Terminal Groups Attached to a Linear Spacer Unit
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Four new host compounds of dumbbell shape featuring bulky 2,3,4,5-tetraphenylcyclopenta-2,4-dien-1-ol moieties attached to both ends of a linear spacer element of different lengths comprising both 1,4-phenylene and ethynylene subunits are synthesized and
- Ruffani, Alexander,Seichter, Wilhelm,Schwarzer, Anke,Weber, Edwin
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p. 3826 - 3837
(2016/07/16)
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- Electrochemically active porous organic polymers based on corannulene
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For the first time, porous organic polymers (POPs) based on the smallest buckybowl, corannulene (BB-POPs) have been synthesized. Three POPs were synthesised via Sonogashira co-polymerization of 1,2,5,6-tetrabromocorannulene and alkyne linkers. BB-POP-3 exhibits the highest surface area (SABET = 560 m2 g-1) and CO2 adsorption of 11.7 wt%, while they retain the redox properties of corannulene.
- Karunathilake, Arosha A.K.,Thompson, Christina M.,Perananthan, Sahila,Ferraris, John P.,Smaldone, Ronald A.
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supporting information
p. 12881 - 12884
(2016/11/06)
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- Polytriazole bridged with 2,5-diphenyl-1,3,4-oxadiazole moieties: A highly sensitive and selective fluorescence chemosensor for Ag+
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Fluorescent conjugated polytriazoles (FCP 1-4) containing both 2,5-diphenyl-1,3,5-oxadiazole (OXD) and 1,2,3-triazole moieties in the main chain were synthesized from aromatic diazide (1) and dialkynes (2-5) via click polymerization, respectively. In the polymers, OXDs (fluorophores) and triazole rings (generated via CuAAC acting as metal ion ligands) comprise a fluorescent system. The polytriazoles displayed relatively strong emission with quantum yields in the range of 0.20-0.28 at room temperature in DMF. The study on their ion-responsive properties showed that, although all four FCPs have good selectivity for Ag+, the integration of alkoxy side groups (methoxy for FCP 2, hexyloxy for FCP 3 and 2-ethylhexyloxy for FCP 4) to the main chains of the polytriazoles decreased their sensitivity for Ag+via alteration of the polymer aggregation status and electron density of the main chains. Thus FCP 1 is highly sensitive for Ag+, where its Ksv is as high as 1.44 × 105 M-1 and its lowest detection limit is in the ppb range (4.22 × 10-7 M). This study provides an efficient click approach to the synthesis of a novel fluorescence sensor for Ag+ detection, which could expand the application of click polymerization in designing fluorescence sensors based on the triazole unit. This journal is
- Cao, Shoupeng,Pei, Zhichao,Xu, Yongqian,Zhang, Ruina,Pei, Yuxin
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p. 45888 - 45896
(2015/06/08)
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- Tetramethoxybenzene is a good building block for molecular wires: Insights from photoinduced electron transfer
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Two donor bridge-acceptor molecules with terminal triarylamine and Ru(bpy)32+ (bpy = 2,2′-bipyridine) redox partners were synthesized and investigated by cyclic voltammetry, optical absorption, luminescence, and transient absorption spectroscopy. The two dyads differ only by the central bridging unit, which was tetramethoxybenzene (tmb) in one case and unsubstituted phenylene (ph) in the other case. Photoirradiation of the Ru(bpy)32+ complex of the two dyads triggers intramolecular electron transfer from the triarylamine to the 3MLCT-excited metal complex, and this process occurs with time constants of 1.5 and 6.8 ns for the tmb- and ph-bridged dyads, respectively. Thermal electron transfer in the reverse direction then leads to disappearance of the photoproduct with a time constant of 10 ns in both dyads. The faster rate of photoinduced charge transfer in the tmb-bridged dyad can be understood in the framework of a hole-tunneling model in which the electron-rich tmb bridge imposes a more shallow barrier than the less electron-rich ph spacer. Until now tmb-based molecular wires have received very little attention, and alkoxy substituents have been mostly used for improving the solubility of oligo-p-phenylene vinylene (OPV) and oligo-p-phenylene ethynylene (OPE) wires. Our study illustrates how four alkoxy-substituents on a phenylene backbone can have a significant influence on the charge-transfer properties of a molecular wire, and this is relevant in the greater context of a future molecular electronics technology.
- Heinz, Luisa G.,Yushchenko, Oleksandr,Neuburger, Markus,Vauthey, Eric,Wenger, Oliver S.
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p. 5676 - 5684
(2015/06/16)
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- Multimetallic Ir-Sn3-catalyzed substitution reaction of π-activated alcohols with carbon and heteroatom nucleophiles
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An atom economic and catalytic substitution reaction of π-activated alcohols by a multimetallic IreSn3 complex has been demonstrated. The multimetallic IreSn3 complex can be easily synthesized from the reaction between [Cp*IrCl2]2 and SnCl2. In presence of as little as 1 mol % of the catalyst three different types of π-activated alcohols, namely benzyl, allyl, and propargyl alcohols, have been successfully transformed into alkylated products using carbon (arenes, heteroarenes, allyltrimethylsilane, and 1,3-dicarbonyls), nitrogen (sulfonamides), oxygen (alcohols), and sulfur (thiols) nucleophiles in very high yields. An electrophilic mechanism is proposed from the Hammett correlation study.
- Maity, Arnab Kumar,Chatterjee, Paresh Nath,Roy, Sujit
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p. 942 - 956
(2013/07/25)
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- A photolabile protection strategy for terminal alkynes
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We present a strategy for photolabile protection of terminal alkynes. Several photo-caged alcohols were synthesized via mild copper(II)-catalyzed substitution between tertiary propargylic alcohols and 2-nitrobenzyl alcohol to build up robust, base stable o-nitrobenzyl (NB) photo-cleavable compounds. We compare the new photolabile protecting group with the commonly used alkyne protecting group, 2-methyl-3-butyn-2-ol and the results show that NB ethers are stable under the cleaving conditions for the cleavage of methylbutynol protected alkynes. Additionally, we present the synthesis of photo-cleavable NB derivatives containing thiol groups that can serve as agents for photoinduced surface functionalization reactions.
- Gschneidtner, Tina A.,Moth-Poulsen, Kasper
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p. 5426 - 5429
(2013/09/23)
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- Conjugated poly(aryleneethynylenesiloles) and their application in detecting explosives
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Hyperbranched and linear conjugated polysiloles incorporating arylene ethynylene subunits (6 and 7) were synthesized by the Sonogashira reaction. The two polymers possess unusual phenomena of PL, with gradual addition of water in their THF solution, the intensity of PL firstly increased and then decreased, this may be due to the aggregate-enhanced emission (AEE) effect and aggregation-caused quenching (ACQ) effect. The polymers function as sensitive fluorescent chemosensors for the detection of explosives, such as picric acid (PA) and TNT. The quenching constants of 6 for PA and TNT were 4.7 × 10-2 ppm-1 and 4.6 × 10-3 ppm -1, respectively. The quenching constants of 7 for PA and TNT were 8.6 × 10-2 ppm-1 and 6.5 × 10-3 ppm-1 respectively. The polymer 7 has more detective efficiency for PA and TNT than that of polymer 6, this may be due to the less steric hindrance.
- Shu, Weifu,Guan, Changwei,Guo, Wenhao,Wang, Chengyun,Shen, Yongjia
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experimental part
p. 3075 - 3081
(2012/06/01)
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- Triazole-pyridine ligands: A novel approach to chromophoric iridium arrays
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We describe a novel modular approach to a series of luminescent iridium complexes bearing triazole-pyridine-derived ligands that were conveniently prepared by using "click" chemistry. One, two or three triazole-pyridine units were effectively built into the heteroaromatic macromolecule using versatile acetylene- and azide-functionalised precursors. Using this approach, a series of iridium-derived molecules, that differ in the number of iridium centres, the structural characteristics of the cyclometalating ligand and the backbone, were synthesised. The preliminary photophysical properties of the prepared complexes indicate that there is only limited interaction (through space or through the backbone) between the iridium centres within one molecule and that each iridium centre retains its individual properties. The results show that our approach can be generally applied towards covalently linked multichromophoric systems with potential application, for instance, in the design and preparation of tunable light emitters. As a demonstration of this concept, a single molecule white-light emitter, constructed from two iridium centres (yellow emission) and a fluorene unit (blue emission), is presented. The Royal Society of Chemistry.
- Juriek, Michal,Felici, Marco,Contreras-Carballada, Pablo,Lauko, Jan,Bou, Sandra Rodriguez,Kouwer, Paul H. J.,Brouwer, Albert M.,Rowan, Alan E.
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supporting information; experimental part
p. 2104 - 2111
(2011/10/02)
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- Rigid rod and tetrahedral hybrid compounds featuring nucleobase and nucleoside End-capped structures
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Being aimed at a new type of porous solids, a moduled design strategy of molecular tectons, making use of the conjugation between a shape defined artificial backbone and the bioinspired molecular fragments of nucleobases or nucleobase derivatives as functional end-caps, has been developed. This led to the formation of the new hybrid compounds 1-13 of linear and tetrahedral geometry, containing uracil, adenine, adenosine, guanosine and its acylated analogs as the sticky end-cap sites. The compounds were synthesized from a halogen or ethynyl substituted nucleobase component and the corresponding ethynylated spacer unit following a metal assisted coupling process as the key reaction step. X-Ray crystal structure analysis demonstrates that the parent compound 1 is a solvent complex with DMSO (1:2), showing the DMSO molecules incorporated in a hydrogen bonded layer structure. Specific dependencies of the fluorescence properties of the new compounds in solution on the structure of the molecules are reported. A selection of solid compounds has been studied in respect of their ability to adsorb organic vapours. They revealed significant differences both in the sorption capacity and the selectivity towards particular solvent vapours.
- Schindler, Diana,Eissmann, Frank,Weber, Edwin
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scheme or table
p. 3549 - 3560
(2010/01/06)
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- A copper- and amine-free Sonogashira reaction employing aminophosphines as ligands
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An efficient Pd-catalyzed Sonogashira coupling reaction was achieved in the absence of a copper salt or amine with an inorganic base and easily prepared, air-stable aminophosphine ligands in commonly used organic solvents; good to excellent yields were ob
- Cheng, Jiang,Sun, Yanhui,Wang, Feng,Guo, Minjie,Xu, Jian-Hua,Pan, Yi,Zhang, Zhaoguo
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p. 5428 - 5432
(2007/10/03)
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- Convenient preparation of di- and tri-ethynylbenzenes by cleavage of 2-hydroxy-2-methylbut-3-yn-4-yl-benzenes with water miscible reagents
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2-Hydroxy-2-methylbut-3-yn-4-yl-benzenes, readily available from bromobenzenes, are efficiently cleaved by the water-miscible reagents sodium 2-propoxide in 2-propanol, or potassium hydroxide in dioxan, which facilitatese isolation of volatile ethynylbenzenes.
- MacBride, J.A. Hugh,Wade, Kenneth
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p. 2309 - 2316
(2007/10/03)
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- Synthesis of an optically active poly(aryleneethynylene) containing extended conjugation in the repeat unit
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A binaphthyl-based chiral poly(aryleneethynylene) (R)-9 that contains significantly longer conjugated repeat unit than the previously reported such materials has been synthesized. GPC analysis of (R)-9 shows that its molecular weight is Mw = 38,200 and Mn
- Ma, Liang,Hu, Qiao-Sheng,Pu, Lin
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p. 3103 - 3106
(2007/10/03)
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