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Search for "actinometry" in Full Text gives 10 result(s) in Beilstein Journal of Organic Chemistry.
A fiber-optic spectroscopic setup for isomerization quantum yield determination
Beilstein J. Org. Chem. 2024, 20, 1684–1692, doi:10.3762/bjoc.20.150
- actinometry, thus demonstrating the reliability of our setup. Keywords: isomerization; molecular photoswitches; photochemistry; photon flux; UV–vis spectroscopy; Introduction Photoswitches are molecules that can undergo a light-driven structural rearrangement to populate a metastable state of the initial
- actinometers are being proposed [41][42], actinometry is dependent on quantum yields determined decades ago [10][43]. Using chemical actinometers is often labor-intensive, and measurements are restricted to irradiation wavelengths where the actinometer absorbs. With high-quality and reliable thermopile and
- the positive features of the aforementioned designs, which can be used to determine the forward and backward quantum yields of molecular switches without the need for actinometry, by combining fiber-coupled LEDs with a commercially calibrated thermopile detector and following the isomerization of a
Mechanistic investigations of polyaza[7]helicene in photoredox and energy transfer catalysis
Beilstein J. Org. Chem. 2024, 20, 1236–1245, doi:10.3762/bjoc.20.106
- determine the ISC quantum yield, ΦISC, using the well-studied photosensitizer [Ru(bpy)3]Cl2 (Rubpy) as reference for actinometry [78][79][80]. This approach involved employing identical excitation conditions at 355 nm (Figure 4A) and monitoring the GSB of Rubpy with a literature-reported difference
- the reliability of our procedure. Taking the literature-known extinction coefficient of the methyl viologen radical cation Δε395(MV•+) ≈ 39000 M−1 cm−1 [82] to calculate its concentration and the initial Aza-H excited-state concentration obtained through Rubpy* actinometry allows us to determine the
- recorded after 0.1 µs (red) and in the presence of TsNa after 0.1 µs, 1 µs and 10 µs (purple). Inset: Kinetic traces at 460 nm. Data sets employed for the calculation ΦISC of Aza-H based on the ground state bleach of Rubpy as the actinometry reference signal following excitation by 355 nm laser pulses with
Optimizing reaction conditions for the light-driven hydrogen evolution in a loop photoreactor
Beilstein J. Org. Chem. 2024, 20, 74–91, doi:10.3762/bjoc.20.9
- actinometry. The system displayed exceptional stability, with operation sustained over 70 hours. A design of experiment (DOE) analysis was used to systematically investigate the influence of key parameters – photon flux, photocatalyst loading, stirring speed, and inert gas flow rate – on the hydrogen
- . Photonic characterization The loop photoreactor using 6 LEDs was photonically characterized by chemical actinometry. Figure 6 shows the actinometer conversions and calculated photon fluxes at different irradiation times. The reasonable linear fits of the conversion (see Figure 6a) prove the applicability
- LEDs electrical current (see Figure 7). The good linear regression shows that the chemical actinometry gave quite reliable photon flux values in the loop photoreactor. This relation was used to extrapolate the photon fluxes for experiments with more than 6 LEDs or with higher electrical current. Light
Selectivity control towards CO versus H2 for photo-driven CO2 reduction with a novel Co(II) catalyst
Beilstein J. Org. Chem. 2023, 19, 1766–1775, doi:10.3762/bjoc.19.129
- from Shimadzu (GC-2030) equipped with two barrier discharge ionization detectors (BID). Every test was repeated at least twice. The photon flux was evaluated with actinometry, according to a previously published procedure [42], and it was 0.025 µE s−1. Therefore, an apparent photoluminescent quantum
Insight into functionalized-macrocycles-guided supramolecular photocatalysis
Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15
- authenticated by isothermal calorimetric titration or fluorescence titration and stopped-flow analysis. Furthermore, the quantum yield and reaction velocity of the photocatalysis can be verified by actinometry and UV–vis measurements. Therefore, with the aid of various analytical and spectroscopic studies, we
Distinctive reactivity of N-benzylidene-[1,1'-biphenyl]-2-amines under photoredox conditions
Beilstein J. Org. Chem. 2020, 16, 1335–1342, doi:10.3762/bjoc.16.114
- the formation of mixtures of several types of amine compounds. A photochemical quantum yield, determined by using the standard ferrioxalate actinometry, was 83% for the radical cross-coupling between 1a and Cy2NMe (see Supporting Information File 1 for details). Next, the homocoupling reactions of
Photoreversible stretching of a BAPTA chelator marshalling Ca2+-binding in aqueous media
Beilstein J. Org. Chem. 2019, 15, 2801–2811, doi:10.3762/bjoc.15.273
- and 0.230 μM for 1Z were determined. The value for 1E is similar to the Kd value reported for BAPTA (Kd = 0.110 μM) and importantly calcium binding by the cis-form was circa 2.5-fold less than that of the trans-form [39]. This is conducive to photopromoted ion release. Chemical actinometry afforded
A photochemical determination of luminescence efficiency of upconverting nanoparticles
Beilstein J. Org. Chem. 2019, 15, 2671–2677, doi:10.3762/bjoc.15.260
- efficiency of these green-emitting “nanolamps”. The agreement of the collected data with the previous published results validates this approach. Keywords: actinometry; diarylethene; lanthanide; photochemistry; upconverting nanoparticle; Introduction The photophysical property of converting low-energy light
- measurement problem. The chemical measurement of light intensity is called actinometry and relies on the exposure of a fully standardized photosensitive compound to the light to be measured [22]. The rate of the photochemical transformation is then used to retrieve the light intensity of the beam exciting the
- solution. Compared to physical radiometry, actinometry is directly transposable to the monitoring of photochemical transformations as it originates from the very same concept and can be performed in the same experimental conditions. It is also adapted to turbid mixtures and can be extended to polychromatic
On the mechanism of photocatalytic reactions with eosin Y
Beilstein J. Org. Chem. 2014, 10, 981–989, doi:10.3762/bjoc.10.97
- answers to the distinction between photocatalytic and radical chain mechanisms can be derived directly from Φ. A quantification of the photon flux is rather problematic. Recently, devices became available which use solar cells for the direct measurement of photon fluxes [33]. However, chemical actinometry
- ][18][19][20][21]. For more details on the actinometry experiments and quantum yield determinations, see Supporting Information File 1. The observed quantum yields Φ of the studied reactions varied by almost two orders of magnitude, between 4.7 and 0.075. This already indicates the operation of
A divergent asymmetric approach to aza-spiropyran derivative and (1S,8aR)-1-hydroxyindolizidine
Beilstein J. Org. Chem. 2007, 3, No. 41, doi:10.1186/1860-5397-3-41
- Spiroketals and the corresponding aza-spiroketals are the structural features found in a number of bioactive natural products, and in compounds possessing photochromic properties for use in the area of photochemical erasable memory, self-development photography, actinometry, displays, filters, lenses of
- with the corresponding non-spiro analogue D, is a well known class of compounds possessing photochromic properties for use in the area of photochemical erasable memory,[10] and also found applications as self-development photography, actinometry, displays, filters, lenses of variable optical density
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