Three compounds with phenyl (
), 4-
-butylphenyl (
) and 4-
,
-diphenylaminophenyl (
) groups attached to bis(fluoromesityl)boryl ((FMes)
B) through B-C bonds have been prepared. The restricted ...rotation about the B-C bonds of boron-bonded aryl rings in solution has been studied by variable-temperature
F NMR spectroscopy, and through-space F-F coupling has been observed for
at low temperature. Steric congestion inhibits binding of
by Lewis bases DABCO and
Bu
P and the activation of H
in their presence. Photophysical and electrochemical studies have been carried out on
,
, and an analogue of
containing a bis(mesityl)boryl ((Mes)
B) group, namely
. Both
and
show bright emission in nonpolar solvents and in the solid-state, very strong electron-accepting ability as measured by cyclic voltammetry, and good air-stability. In addition,
displayed unusually long-lived emission (
= 2.47 s) in 2-MeTHF at 77 K. The much stronger acceptor strength of (FMes)
B than (Mes)
B leads to significantly red-shifted emission in solution and the solid state, stronger emission solvatochromism, and significantly lower reduction potentials. Theoretical calculations confirm that
and
tend to form highly twisted excited states with good conjugation between one FMes group and the boron atom, which correlate well with their blue-shifted solid-state emissions and low
values in solution.
Hydrogen peroxide (H
O
) is a key reactive oxygen species and a messenger in cellular signal transduction apart from playing a vital role in many biological processes in living organisms. In this ...article, we present phenyl boronic acid-functionalized quinone-cyanine (
) in combination with AT-rich DNA (exogenous or endogenous cellular DNA),
,
⊂DNA as a stimuli-responsive NIR fluorescence probe for measuring
levels of H
O
. In response to cellular H
O
stimulus,
converts into
, a one-donor-two-acceptor (D2A) system that exhibits switch-on NIR fluorescence upon binding to the DNA minor groove. Fluorescence studies on the combination probe
⊂DNA showed strong NIR fluorescence selectively in the presence of H
O
. Furthermore, glucose oxidase (GOx) assay confirmed the high efficiency of the combination probe
⊂DNA for probing H
O
generated
through GOx-mediated glucose oxidation. Quantitative analysis through fluorescence plate reader, flow cytometry and live imaging approaches showed that
is a promising probe to detect the normal as well as elevated levels of H
O
produced by EGF/Nox pathways and post-genotoxic stress in both primary and senescent cells. Overall,
, in combination with exogenous or cellular DNA, is a versatile probe to quantify and image H
O
in normal and disease-associated cells.
The first asymmetric sulfa-Michael addition of thiols to trans-3,3,3-trifluoropropenyl phenyl sulfone for the construction of a unique stereogenic center bearing a trifluoromethyl group and a sulfur ...atom has been achieved in high yields and moderate to good enantioselectivities with 1mol% bifunctional amine–thiourea catalyst.
The first asymmetric sulfa-Michael addition of thiols to trans-3,3,3-trifluoropropenyl phenyl sulfone for the construction of a unique stereogenic center bearing a trifluoromethyl group and a sulfur atom has been achieved in high yields and moderate to good enantioselectivities with 1mol% bifunctional amine–thiourea catalyst.
A series of cyclometalated iridium(iii) complexes Ir(C^N)
(N^N)PF
(N^N = 2,2'-bipyridine (
), 6-phenyl-2,2'-bipyridine (
), 4,4'-di-
-butyl-2,2'-bipyridine (
), 4,4'-di-
...-butyl-6-phenyl-2,2'-bipyridine (
); HC^N = 2-(3-phenyl)phenylpyridine (HPhppy) or 2-(3,5-diphenyl)phenylpyridine (HPh
ppy)) are reported. They have been synthesized using solvento precursors so as to avoid the use of chlorido-dimer intermediates, chloride ion contaminant being detrimental to the performance of Ir(C^N)
(N^N)PF
emitters in light-electrochemical cell (LEC) devices. Single crystal structure determinations and variable temperature solution
H NMR spectroscopic data confirm that the pendant phenyl domains engage in multiple face-to-face π-interactions within the coordination sphere of the iridium(iii) centre. The series of Ir(Phppy)
(N^N)
and Ir(Ph
ppy)
(N^N)
complexes investigated include those with and without intra-cation face-to-face π-stacking. All the complexes display excellent luminescent properties, in particular when employed in thin solid films. The most important observation is that all the LECs using the Ir(Phppy)
(N^N)
and Ir(Ph
ppy)
(N^N)
emitters (
with and without intra-cation π-stacking interactions) exhibit very stable luminance outputs over time, even when driven at elevated current densities. The most stable LEC had an extrapolated lifetime of more than 2500 hours under accelerated testing conditions.
The thermal behaviour of Polystyrene (PS) based nanocomposites, loaded with different percentage of a novel Polyhedral Oligomeric Silsesquioxane (POSS) of general formula R7R′(SiO1.5)8, where ...R = phenyl and R′ = (CH2)9CH3, was studied in both inert (flowing nitrogen) and oxidative (static air) atmospheres. Nanocomposites were prepared by in situ polymerization of styrene, in the presence of the appropriate POSS, and were characterized by Differential Scanning Calorimetry (DSC), to determine glass transition temperature (Tg), and by FTIR and 1H NMR spectroscopy, to verify and quantify the filler content into the polymeric matrix. Degradations were carried out into a thermobalance at various heating rates in the 25–700 °C temperature range. The characteristic parameters of thermal stability, namely temperature at 5% mass loss (T5%) and the activation energy (Ea) of degradation, were determined. The data obtained were then compared with each other and with those obtained in the past by our group on the mutual alkyl-POSSs/PS nanocomposites to verify the influence of the vertices of POSS cage on the compatibility with the polymeric matrix and on the thermal stability of the synthesized materials.
A simple structural design principle and band position alignment of conjugated microporous polymers for enhanced photocatalytic efficiency is presented. The valence and conduction band positions of ...the polymer networks can be fine‐tuned by altering the substitution positions on the centered phenyl unit to match the required redox potential of the catalytic reactions under visible light.
An unexpected route for the synthesis of N,N-dialkyl formamidines has been reported by the reaction of amines with N,N-dialkyl formamides and phenyl chloroformate.
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Gold‐catalyzed cycloadditions of ynamides with azidoalkenes or 2H‐azirines give 3+2 or 4+3 formal cycloadducts of three classes. Cycloadditions of ynamides with 2H‐azirine species afford pyrrole ...products with two regioselectivities when the Cβ‐substituted 2H‐azirine is replaced from an alkyl (or hydrogen) with an ester group. For ynamides substituted with an electron‐rich phenyl group, their reactions with azidoalkenes proceed through novel 4+3 cycloadditions to deliver 1H‐benzodazepine products instead.
Completing the ring: Gold‐catalyzed cycloadditions of ynamides with azidoalkenes or 2H‐azirines give three distinct classes of 3+2 or 4+3 cycloadducts, depending on the types of the initial ynamides and 2H‐azirines (see scheme; EWG=electron‐withdrawing group).
Capturing volatile radionuclide iodine from nuclear and medical waste streams is an important environmental issue. In this work, we found that the 2,6-position hydrogen atoms of a BODIPY core undergo ...fast iodination with volatile iodine at room temperature. Inspired by our observation, two novel BODIPY-based conjugated porous polymers (CPPs) BDP-CPP-1 and BDP-CPP-2, and the reference compound NBDP-CPP, were prepared, which were designed and then synthesized via the Sonogashira cross-coupling reaction of 1,3,5-triethynyl-benzene (TEB) and dibromo-substituted derivatives. With the coexistence of the BODIPY units and plenty of triple bonds and phenyl rings that could adsorb iodine with high capacity and affinity, compounds BDP-CPP-1 and BDP-CPP-2 exhibited satisfactory iodine adsorption capacities of 2830 mg g-1 and 2230 mg g-1, respectively. Moreover, BDP-CPP-1 was shown to adsorb volatile iodine through a chemical mechanism involving the 2,6-position hydrogen atoms of the BODIPY core. Surprisingly, the active sites on the BODIPY units for a chemical iodination reaction were mostly eliminated as a result of the crosslinking of BODIPY units during the Sonogashira coupling reaction. The preliminary results demonstrated that the iodine uptake abilities, which are in the order of BDP-CPP-1 > BDP-CPP-2 > NBDP-CPP, are not only dependent on the surface area, but also on the BODIPY units. The BDP-CPPs show high thermal stability with a decomposition temperature of about 300 degree C. In addition, the BDP-CPPs demonstrated remarkable recyclability. Due to the highly pi -conjugated porous structure along with the high affinity for iodine molecules and iodination sites, some BODIPY-based CPPs may provide a feasible pathway to adsorb other volatile compounds.
The B2PLYP double hybrid functional, coupled with the correlation-consistent triple-ζ cc-pVTZ (VTZ) basis set, has been validated in the framework of the semiexperimental (SE) approach for deriving ...accurate equilibrium structures of molecules containing up to 15 atoms. A systematic comparison between new B2PLYP/VTZ results and several equilibrium SE structures previously determined at other levels, in particular B3LYP/SNSD and CCSD(T) with various basis sets, has put in evidence the accuracy and the remarkable stability of such model chemistry for both equilibrium structures and vibrational corrections. New SE equilibrium structures for phenylacetylene, pyruvic acid, peroxyformic acid, and phenyl radical are discussed and compared with literature data. Particular attention has been devoted to the discussion of systems for which lack of sufficient experimental data prevents a complete SE determination. In order to obtain an accurate equilibrium SE structure for these situations, the so-called templating molecule approach is discussed and generalized with respect to our previous work. Important applications are those involving biological building blocks, like uracil and thiouracil. In addition, for more general situations the linear regression approach has been proposed and validated.
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