@article{14776, abstract = {Soluble chaperones residing in the endoplasmic reticulum (ER) play vitally important roles in folding and quality control of newly synthesized proteins that transiently pass through the ER en route to their final destinations. These soluble residents of the ER are themselves endowed with an ER retrieval signal that enables the cell to bring the escaped residents back from the Golgi. Here, by using purified proteins, we showed that Nicotiana tabacum phytaspase, a plant aspartate-specific protease, introduces two breaks at the C-terminus of the N. tabacum ER resident calreticulin-3. These cleavages resulted in removal of either a dipeptide or a hexapeptide from the C-terminus of calreticulin-3 encompassing part or all of the ER retrieval signal. Consistently, expression of the calreticulin-3 derivative mimicking the phytaspase cleavage product in Nicotiana benthamiana cells demonstrated loss of the ER accumulation of the protein. Notably, upon its escape from the ER, calreticulin-3 was further processed by an unknown protease(s) to generate the free N-terminal (N) domain of calreticulin-3, which was ultimately secreted into the apoplast. Our study thus identified a specific proteolytic enzyme capable of precise detachment of the ER retrieval signal from a plant ER resident protein, with implications for the further fate of the escaped resident.}, author = {Teplova, Anastasiia and Pigidanov, Artemii A. and Serebryakova, Marina V. and Golyshev, Sergei A. and Galiullina, Raisa A. and Chichkova, Nina V. and Vartapetian, Andrey B.}, issn = {1422-0067}, journal = {International Journal of Molecular Sciences}, keywords = {Inorganic Chemistry, Organic Chemistry, Physical and Theoretical Chemistry, Computer Science Applications, Spectroscopy, Molecular Biology, General Medicine, Catalysis}, number = {22}, publisher = {MDPI}, title = {{Phytaspase Is capable of detaching the endoplasmic reticulum retrieval signal from tobacco calreticulin-3}}, doi = {10.3390/ijms242216527}, volume = {24}, year = {2023}, } @article{12919, abstract = {We report the visible light photocatalytic cleavage of trityl thioethers or ethers under pH-neutral conditions. The method results in the formation of the respective symmetrical disulfides and alcohols in moderate to excellent yield. The protocol only requires the addition of a suitable photocatalyst and light rendering it orthogonal to several functionalities, including acid labile protective groups. The same conditions can be used to directly convert trityl-protected thiols into unsymmetrical disulfides or selenosulfides, and to cleave trityl resins in solid phase organic synthesis.}, author = {Murakami, Sho and Brudy, Cosima and Bachmann, Moritz and Takemoto, Yoshiji and Pieber, Bartholomäus}, issn = {1437-210X}, journal = {Synthesis}, keywords = {Organic Chemistry, Catalysis}, number = {09}, pages = {1367--1374}, publisher = {Georg Thieme Verlag}, title = {{Photocatalytic cleavage of trityl protected thiols and alcohols}}, doi = {10.1055/a-1979-5933}, volume = {55}, year = {2023}, } @article{12920, abstract = {The multicomponent approach allows to incorporate several functionalities into a single covalent organic framework (COF) and consequently allows the construction of bifunctional materials for cooperative catalysis. The well-defined structure of such multicomponent COFs is furthermore ideally suited for structure-activity relationship studies. We report a series of multicomponent COFs that contain acridine- and 2,2’-bipyridine linkers connected through 1,3,5-benzenetrialdehyde derivatives. The acridine motif is responsible for broad light absorption, while the bipyridine unit enables complexation of nickel catalysts. These features enable the usage of the framework materials as catalysts for light-mediated carbon−heteroatom cross-couplings. Variation of the node units shows that the catalytic activity correlates to the keto-enamine tautomer isomerism. This allows switching between high charge-carrier mobility and persistent, localized charge-separated species depending on the nodes, a tool to tailor the materials for specific reactions. Moreover, nickel-loaded COFs are recyclable and catalyze cross-couplings even using red light irradiation.}, author = {Traxler, Michael and Reischauer, Susanne and Vogl, Sarah and Roeser, Jérôme and Rabeah, Jabor and Penschke, Christopher and Saalfrank, Peter and Pieber, Bartholomäus and Thomas, Arne}, issn = {1521-3765}, journal = {Chemistry – A European Journal}, keywords = {General Chemistry, Catalysis, Organic Chemistry}, number = {4}, publisher = {Wiley}, title = {{Programmable photocatalytic activity of multicomponent covalent organic frameworks used as metallaphotocatalysts}}, doi = {10.1002/chem.202202967}, volume = {29}, year = {2023}, } @article{12921, abstract = {Visible-light photocatalysis provides numerous useful methodologies for synthetic organic chemistry. However, the mechanisms of these reactions are often not fully understood. Common mechanistic experiments mainly aim to characterize excited state properties of photocatalysts and their interaction with other species. Recently, in situ reaction monitoring using dedicated techniques was shown to be well-suited for the identification of intermediates and to obtain kinetic insights, thereby providing more holistic pictures of the reactions of interest. This minireview surveys these technologies and discusses selected examples where reaction monitoring was used to elucidate the mechanism of photocatalytic reactions.}, author = {Madani, Amiera and Pieber, Bartholomäus}, issn = {1867-3899}, journal = {ChemCatChem}, keywords = {Inorganic Chemistry, Organic Chemistry, Physical and Theoretical Chemistry, Catalysis}, number = {7}, publisher = {Wiley}, title = {{In situ reaction monitoring in photocatalytic organic synthesis}}, doi = {10.1002/cctc.202201583}, volume = {15}, year = {2023}, } @article{12939, abstract = {Linear tetrapyrroles, called phyllobilins, are obtained as major catabolites upon chlorophyll degradation. Primarily, colorless phylloleucobilins featuring four deconjugated pyrrole units were identified. Their yellow counterparts, phylloxanthobilins, were discovered more recently. Although the two catabolites differ only by one double bond, physicochemical properties are very distinct. Moreover, the presence of the double bond seems to enhance physiologically relevant bioactivities: in contrast to phylloleucobilin, we identified a potent anti-proliferative activity for a phylloxanthobilin, and show that this natural product induces apoptotic cell death and a cell cycle arrest in cancer cells. Interestingly, upon modifying inactive phylloleucobilin by esterification, an anti-proliferative activity can be observed that increases with the chain lengths of the alkyl esters. We provide first evidence for anti-cancer activity of phyllobilins, report a novel plant source for a phylloxanthobilin, and by using paper spray MS, show that these bioactive yellow chlorophyll catabolites are more prevalent in Nature than previously assumed.}, author = {Karg, Cornelia A. and Wang, Pengyu and Kluibenschedl, Florian and Müller, Thomas and Allmendinger, Lars and Vollmar, Angelika M. and Moser, Simone}, issn = {1434-193X}, journal = {European Journal of Organic Chemistry}, keywords = {Organic Chemistry, Physical and Theoretical Chemistry}, number = {29}, pages = {4499--4509}, publisher = {Wiley}, title = {{Phylloxanthobilins are abundant linear tetrapyrroles from chlorophyll breakdown with activities against cancer cells}}, doi = {10.1002/ejoc.202000692}, volume = {2020}, year = {2020}, } @article{13369, abstract = {Arylazopyrazoles represent a new family of molecular photoswitches characterized by a near-quantitative conversion between two states and long thermal half-lives of the metastable state. Here, we investigated the behavior of a model arylazopyrazole in the presence of a self-assembled cage based on Pd–imidazole coordination. Owing to its high water solubility, the cage can solubilize the E isomer of arylazopyrazole, which, by itself, is not soluble in water. NMR spectroscopy and X-ray crystallography have independently demonstrated that each cage can encapsulate two molecules of E-arylazopyrazole. UV-induced switching to the Z isomer was accompanied by the release of one of the two guests from the cage and the formation of a 1:1 cage/Z-arylazopyrazole inclusion complex. DFT calculations suggest that this process involves a dramatic change in the conformation of the cage. Back-isomerization was induced with green light and resulted in the initial 1:2 cage/E-arylazopyrazole complex. This back-isomerization reaction also proceeded in the dark, with a rate significantly higher than in the absence of the cage.}, author = {Hanopolskyi, Anton I and De, Soumen and Białek, Michał J and Diskin-Posner, Yael and Avram, Liat and Feller, Moran and Klajn, Rafal}, issn = {1860-5397}, journal = {Beilstein Journal of Organic Chemistry}, keywords = {Organic Chemistry}, pages = {2398--2407}, publisher = {Beilstein Institut}, title = {{Reversible switching of arylazopyrazole within a metal–organic cage}}, doi = {10.3762/bjoc.15.232}, volume = {15}, year = {2019}, } @article{13379, author = {Bléger, David and Klajn, Rafal}, issn = {1521-3927}, journal = {Macromolecular Rapid Communications}, keywords = {Materials Chemistry, Polymers and Plastics, Organic Chemistry}, number = {1}, publisher = {Wiley}, title = {{Integrating macromolecules with molecular switches}}, doi = {10.1002/marc.201700827}, volume = {39}, year = {2018}, } @article{13383, abstract = {Two novel donor–acceptor Stenhouse adducts (DASAs) featuring the catechol moiety were synthesized and characterized. Both compounds bind strongly to the surfaces of magnetite nanoparticles. An adrenaline-derived DASA renders the particles insoluble in all common solvents, likely because of poor solvation of the zwitterionic isomer generated on the nanoparticle surfaces. Well-soluble nanoparticles were successfully obtained using dopamine-derived DASA equipped with a long alkyl chain. Upon its attachment to nanoparticles, this DASA undergoes an irreversible decoloration reaction owing to the formation of the zwitterionic form. The reaction follows first-order kinetics and proceeds more rapidly on large nanoparticles. Interestingly, decoloration can be suppressed in the presence of free DASA molecules in solution or at high nanoparticle concentrations.}, author = {Ahrens, Johannes and Bian, Tong and Vexler, Tom and Klajn, Rafal}, issn = {2367-0932}, journal = {ChemPhotoChem}, keywords = {Organic Chemistry, Physical and Theoretical Chemistry, Analytical Chemistry}, number = {5}, pages = {230--236}, publisher = {Wiley}, title = {{Irreversible bleaching of donor-acceptor stenhouse adducts on the surfaces of magnetite nanoparticles}}, doi = {10.1002/cptc.201700009}, volume = {1}, year = {2017}, } @article{13405, abstract = {We report a method for preparing electrode–molecule–electrode junctions that incorporate nonsymmetrical azobenzene dithiols. Our approach is based on sequential deprotection of thiol moieties originally carrying two different protecting groups. The azobenzene derivatives retained their switching properties within monolayers and permitted the photocontrol of electrical conductance.}, author = {Ely, Tal and Das, Sanjib and Li, Wenjie and Kundu, Pintu and Tirosh, Einat and Cahen, David and Vilan, Ayelet and Klajn, Rafal}, issn = {1437-2096}, journal = {Synlett}, keywords = {Organic Chemistry}, number = {18}, pages = {2370--2374}, publisher = {Georg Thieme Verlag}, title = {{Photocontrol of electrical conductance with a nonsymmetrical azobenzene dithiol}}, doi = {10.1055/s-0033-1340087}, volume = {24}, year = {2013}, } @article{10392, abstract = {Protonated formylmetallocenes [M(C5H5)(C5H4-CHOH)]+ (M = Fe, Ru) and their isomers have been studied at the BP86 and B3LYP levels of density functional theory. Oxygen-protonated isomers are the most stable forms in each case, with a plethora of ring- or metal-protonated species at least ca. 14 and 10 kcal/mol higher in energy for M = Fe and Ru, respectively. The computed rotational barriers around the C−C bond connecting the cyclopentadienyl and protonated formyl moieties, ca. 18 kcal/mol, are indicative of substantial conjugation between these moieties. Some of the ring- and iron-protonated species are models for possible intermediates in Friedel–Crafts acylation of ferrocene, and the computations provide further evidence that exo attack is clearly favored over endo attack of the electrophile in this reaction. The structures of the most stable mono- and diprotonated formylferrocenes are corroborated by the good agreement between GIAO-B3LYP-computed and experimental NMR chemical shifts.}, author = {Šarić, Anđela and Vrček, Valerije and Bühl, Michael}, issn = {1520-6041}, journal = {Organometallics}, keywords = {Inorganic Chemistry, Organic Chemistry, Physical and Theoretical Chemistry}, number = {3}, pages = {394--401}, publisher = {American Chemical Society}, title = {{Density functional study of protonated formylmetallocenes}}, doi = {10.1021/om700916f}, volume = {27}, year = {2008}, } @article{13433, abstract = {Self-assembled monolayers (SAMs) of alkane thiols on gold and other metals are versatile constructs with which to study interfacial phenomena and reactions at surfaces. Surface properties of SAMs - e.g., wettability, stability in diverse environments, propensity to interact with or to resist adsorption of macromolecules -- depend on and can be controlled flexibly by the properties of the functional (head) groups in the w position of the alkyl chain. SAMs provide a basis for many important scientific and technological applications, ranging from micropatterning methods, through sensing, to biological recognition. Despite their importance, the literature on SAMs and the synthesis of molecules that constitute them remains scattered and often conflicting. The purpose of this Review is (i) to summarize the applications and physical properties of SAMs and (ii) to systematize the strategies of synthesis of ω-functionalized alkane thiols. Generic retrosynthetic scheme is developed that allows efficient synthetic planning. Issues related to the selection of appropriate protecting groups and the ways of introduction of the thiol functionality are discussed in detail, and illustrated with examples of syntheses of several complex alkane thiols.}, author = {Witt, Dariusz and Klajn, Rafal and Barski, Piotr and Grzybowski, Bartosz}, issn = {1875-5348}, journal = {Current Organic Chemistry}, keywords = {Organic Chemistry}, number = {18}, pages = {1763--1797}, publisher = {Bentham Science}, title = {{Applications, properties and synthesis of w-functionalized n-alkanethiols and disulfides - the building blocks of self-assembled monolayers}}, doi = {10.2174/1385272043369421}, volume = {8}, year = {2005}, } @article{13436, abstract = {Cross-metathesis reactions of α,β-unsaturated sulfones and sulfoxides in the presence of molybdenum and ruthenium pre-catalysts were tested. A selective metahesis reaction was achieved between functionalized terminal olefins and vinyl sulfones by using the ‘second generation’ ruthenium catalysts 1c–h while the highly active Schrock catalyst 1b was found to be functional group incompatible with vinyl sulfones. The cross-metathesis products were isolated in good yields with an excellent (E)-selectivity. Both the molybdenum and ruthenium-based complexes were, however, incompatible with α,β- and β,γ-unsaturated sulfoxides.}, author = {Michrowska, Anna and Bieniek, Michał and Kim, Mikhail and Klajn, Rafal and Grela, Karol}, issn = {1464-5416}, journal = {Tetrahedron}, keywords = {Organic Chemistry, Drug Discovery, Biochemistry}, number = {25}, pages = {4525--4531}, publisher = {Elsevier}, title = {{Cross-metathesis reaction of vinyl sulfones and sulfoxides}}, doi = {10.1016/s0040-4020(03)00682-3}, volume = {59}, year = {2003}, } @article{13437, abstract = {Liquid/liquid Phase Transfer Catalysis (PTC) reaction of 4-chlorobutyronitrile with nonenolisable aldehydes leads via an addition-cyclisation reaction sequence to derivatives of tetrahydrofuran-3-carbonitrile.}, author = {Macogonkosza, Mieczysław and Przyborowski, Jacek and Klajn, Rafal and Kwast, Andrzej}, issn = {1437-2096}, journal = {Synlett}, keywords = {Organic Chemistry}, number = {12}, pages = {1773--1774}, publisher = {Georg Thieme Verlag}, title = {{Simple synthesis of 2-substituted Tetrahydrofuran-3-carbonitriles}}, doi = {10.1055/s-2000-8670}, volume = {2000}, year = {2000}, }