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Some types of dioxetanes are called chemiluminophores because they produce luminescence light without the use of enzymes. Here, we designed and synthesized a novel carboxy group-containing chemiluminophore derivative, which enabled the simple introduction of such a chemiluminophore to the molecule of interest. Furthermore, we demonstrate that the in vivo imaging system (IVIS imaging system) can recognize tagged chemicals, indicating that such a chemiluminophore could be employed as a tracer molecule for biological studies., (© 2022 Wiley-VCH GmbH.)

Chemiluminescence-based detection methods offer a superior signal-to-noise ratio and are commonly adopted for biosensors. This work presents the design and implementation of a supramolecular assay based on a chemiluminescent chemosensor. Specifically, an indicator displacement assay (IDA) with the supramolecular host-guest complex of chemiluminescent phenoxy 1,2-dioxetane and cucurbit[8]uril enables the low-micromolar detection of drugs in human urine and human serum samples. Cucurbit[8]uril thereby acts as a non-surfactant chemiluminescence enhancer and a synthetic receptor. Additionally, we show that adding an equimolar amount of cucurbit[8]uril to a commercially available dioxetane used in standard enzymatic chemiluminescence immunoassays enhances the chemiluminescence by more than 15 times. Finally, we demonstrate that a chemiluminescence resonance energy transfer between a unimolecular macrocyclic cucurbit[7]uril-dye conjugate and a phenoxy 1,2-dioxetane can be utilized to detect the herbicide paraquat at a micromolar concentration in aqueous media.

UV-like DNA damage is created in the dark by chemiexcitation, in which UV-activated enzymes generate reactive oxygen and nitrogen species that create a dioxetane on melanin. Thermal cleavage creates an electronically excited triplet-state carbonyl whose high energy transfers to DNA. Screening natural compounds for the ability to quench this energy identified polyenes, polyphenols, mycosporine-like amino acids, and related compounds better known as antioxidants. To eliminate false positives such as ROS and RNS scavengers, we then used the generator of triplet-state acetone, tetramethyl-1,2-dioxetane (TMD), to excite the triplet-energy reporter 9,10-dibromoanthracene-2-sulfonate (DBAS). Quenching measured as reduction in DBAS luminescence revealed three clusters of 50% inhibitory concentration, ~50 μM, 200-500 μM, and >600 μM, with the former including sorbate, ferulic acid, and resveratrol. Representative triplet-state quenchers prevented chemiexcitation-induced "dark" cyclobutane pyrimidine dimers (dCPD) in DNA and in UVA-irradiated melanocytes. We conclude that (i) the delocalized pi electron cloud that stabilizes the electron-donating activity of many common antioxidants allows the same molecule to prevent an electronically excited species from transferring its triplet-state energy to targets such as DNA and (ii) the most effective class of triplet-state quenchers appear to operate by energy diversion instead of electron donation and dissipate that energy by isomerization.

Carotenoid cleavage dioxygenases (CCDs) comprise a superfamily of mononuclear non-heme iron proteins that catalyze the oxygenolytic fission of alkene bonds in carotenoids to generate apocarotenoid products. Some of these enzymes exhibit additional activities such as carbon skeleton rearrangement and trans-cis isomerization. The group also includes a subfamily of enzymes that split the interphenyl alkene bond in molecules such as resveratrol and lignostilbene. CCDs are involved in numerous biological processes ranging from production of light-sensing chromophores to degradation of lignin derivatives in pulping waste sludge. These enzymes exhibit unique features that distinguish them from other families of non-heme iron enzymes. The distinctive properties and biological importance of CCDs have stimulated interest in their modes of catalysis. Recent structural, spectroscopic, and computational studies have helped clarify mechanistic aspects of CCD catalysis. Here, we review these findings emphasizing common and unique properties of CCDs that enable their variable substrate specificity and regioselectivity. This article is part of a Special Issue entitled Carotenoids recent advances in cell and molecular biology edited by Johannes von Lintig and Loredana Quadro., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier B.V.)

The article introduces a robust algorithm for the computation of minimum energy paths transiting along regions of near-to or degeneracy of adiabatic states. The method facilitates studies of excited state reactivity involving weakly avoided crossings and conical intersections. Based on the analysis of the change in the multiconfigurational wave function the algorithm takes the decision whether the optimization should continue following the same electronic state or switch to a different state. This algorithm helps to overcome convergence difficulties near degeneracies. The implementation in the MOLCAS quantum chemistry package is discussed. To demonstrate the utility of the proposed procedure four examples of application are provided: thymine, asulam, 1,2-dioxetane, and a three-double-bond model of the 11-cis-retinal protonated Schiff base., (© 2015 Wiley Periodicals, Inc.)

The past 10 years have seen a resurgence of interest in the field of polymer mechanochemistry. Whilst the destructive effects of mechanical force on polymer chains have been known for decades, it was only recently that researchers tapped into these forces to realize more useful chemical transformations. The current review discusses the strategic incorporation of weak covalent bonds in polymers to create materials with stress-sensing and damage-repairing properties. Firstly, the development of mechanochromism and mechanoluminescence as stress reporters is considered. The second half focuses on the net formation of covalent bonds as a response to mechanical force, via mechanocatalysis and mechanically unmasked chemical reactivity, and concludes with perspectives for the field.

Dioxetane-based force-induced light emission from polymers, or mechanoluminescence, is a powerful new way of characterizing the behavior of polymeric materials under stress. Here, we reveal that breaking the dioxetane mechanically gives strikingly similar products to those formed on thermal activation, with a singlet/triplet ratio of 1:9.9 and a total quantum yield of 9.8%. A sensitized relay scheme ensured high reproducibility in the detection of the short-lived triplet products. In addition to guiding the design of more sensitive mechanoluminescent probes, the similarity in the scission products indicates that once mechanical force releases the steric lock between the adamantyl groups, the dioxetane undergoes scission in a pathway that resembles the thermal process. Excited states are formed only after the main transition state in a region in which the excited- and ground-state surfaces are nearly degenerate, which, thus, accounts for the remarkable similarity in the scission products., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Bicyclic dioxetanes 2a-c bearing a 2'-alkoxy-2-hydroxy-1,1'-binaphthyl-7-yl moiety were effectively synthesized and their base-induced chemiluminescent decomposition was investigated by the use of alkaline metal (Na(+) and K(+) ) or Mg(2+) alkoxide in MeOH. When 2a-c were treated with tetrabutylammonium fluoride (TBAF) in dimethyl sulfoxide (DMSO) as a reference system, they showed chemiluminescence as a flash of orange light (maximum wavelength λmax (CL)  = 573-577 nm) with efficiency Φ(CL)  = 6-8 × 10(-2) . On the other hand, for an alkaline metal (Na(+) or K(+) ) alkoxide/MeOH system, 2a-c decomposed slowly to emit a glow of chemiluminescence, the spectra of which were shifted slightly toward red from the TBAF/DMSO system, and Φ(CL) (= 1.4-2.3 × 10(-3) ) was considerably decreased. In addition, Mg(OMe)2 was found to play a characteristic role as a base for the chemiluminescent decomposition of 2a-c through coordination to the intermediary oxidoaryl-substituted dioxetanes 13. Thus, Mg(2+) increased Φ(CL) to more than twice those with Na(+) or K(+) , while it shifted λmax (CL) considerably toward blue (λmax (CL)  = 550-566 nm)., (Copyright © 2012 John Wiley & Sons, Ltd.)