Using multiple self-sorting for switching functions in discrete multicomponent systems

• Amit Ghosh and
• Michael Schmittel

Beilstein J. Org. Chem. 2020, 16, 2831–2853, doi:10.3762/bjoc.16.233

• self-sorting protocols. The present mini review will provide an overview over the latest advancements in this field with a focus on reversibly switchable functions in discrete supramolecular systems. Keywords: copper; fluorescence; self-assembly; self-sorting; zinc porphyrin; Introduction Since self

• )] (Figure 4e). Equally, Schalley and Nitschke developed a guest-induced self-sorting based on two new Zn4L6 cages (Figure 5a) using the aldehyde 9 and the diamine subcomponents 7 and 8 that contained either the naphthalene diimide or zinc porphyrin moiety [51]. Both cages respond selectively to distinct

• chemical stimuli yielding different supramolecular products. The porphyrin ligands of the cage [Zn4(8')6]8+ interacted favorably with C70 as a guest, whereas an electron-rich aromatic crown-ether did thread onto the electron-deficient naphthalene diimides of cage [Zn4(7')6]8+ forming mechanically

Synthesis of 4-substituted azopyridine-functionalized Ni(II)-porphyrins as molecular spin switches

• Jannis Ludwig,
• Tobias Moje,
• Fynn Röhricht and
• Rainer Herges

Beilstein J. Org. Chem. 2020, 16, 2589–2597, doi:10.3762/bjoc.16.210

• ], switchable NMR relaxation agents [8][9][10], and building blocks for molecular spintroncis [11]. Our modular design is based on three components: a) a Ni(II)-porphyrin (square planar base complex), b) an azoaryl unit (photoswitchable ligand) and c) a molecular linker or tether (connecting the porphyrin with

• the switchable ligand). This approach has been dubbed “record player” design for obvious reasons (Figure 1a). The Ni-porphyrin (“disk”) is low-spin if the azo-aryl unit (“tone arm”) is in trans configuration. Upon switching to the bent cis configuration, the lone pair of the pyridine (or imidazole

• components (Ni-porphyrin, azo-aryl unit, and tether) have to be carefully designed and tuned regarding their geometry and electronic properties. The Ni-porphyrin should be electron deficient (electron-withdrawing substituents in meso position), the azo-aryl unit should be electron rich (electron-donating

NMR Spectroscopy of supramolecular chemistry on protein surfaces

• Peter Bayer,
• Anja Matena and
• Christine Beuck

Beilstein J. Org. Chem. 2020, 16, 2505–2522, doi:10.3762/bjoc.16.203

• amino substituents can be attached [52][53][54][55][56][57][58][59][60]. Several porphyrin ligands show tight (nM) binding and can cause unfolding of the targeted protein [52][53][54][55]. However, other porphyrin ligands were used to recognize protein surfaces in a native state [56][57], promoted

• indeed recognize the highly positively charged area on cytochrome c (Cyt c) that binds Cyt c peroxidase. The inhibition of this protein–protein interaction was demonstrated as well using a luminescence quenching assay. The protein surface recognition of two porphyrin ligands bearing carboxylate

• docking that the Cyt c/porphyrin complexes exist as a dynamic ensemble where multiple surface patches can transiently interact with the ligand through a combination of hydrophobic interactions with the porphyrin core and electrostatic interactions with the carboxylate substituents. Cucurbit[7]uril and

Azo-dimethylaminopyridine-functionalized Ni(II)-porphyrin as a photoswitchable nucleophilic catalyst

• Jannis Ludwig,
• Julian Helberg,
• Hendrik Zipse and
• Rainer Herges

Beilstein J. Org. Chem. 2020, 16, 2119–2126, doi:10.3762/bjoc.16.179

• Abstract We present the synthesis and the photochemical and catalytic switching properties of an azopyridine as a photoswitchable ligand, covalently attached to a Ni(II)-porphyrin. Upon irradiation with 530 nm (green light), the azopyridine switches to the cis configuration and coordinates with the Ni2

• -epoxypropane to propylene carbonate using an aluminum porphyrin and a photoresponsive ligand. The catalytic activity of the metal porphyrin depended on the axial coordination of an azostilbene and coordination of the latter ligand was controlled by photoisomerization of the stilbene unit [9]. Hecht et al

• by coordination/decoordination to the Ni2+ ion in a Ni-porphyrin. So-called record player molecules, including a Ni(II)-porphyrin as the square planar base complex and azopyridines as photoswitchable axial ligands, were previously investigated for spin switching applications [13][14][15][16][17][18

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

• postsynthetic modifications in flow [63]. Poliakoff, George, and co-workers reported a porphyrin photosensitiser ionically immobilised to sulphonate-cross-linked ion exchange polystyrene resins (amberlyst-15) for the synthesis of artemisinin (49). This resulted in a bifunctional material, which acts as a HPCat

• and heterogeneous Brønsted acid catalyst, which are both required for independent steps in the synthesis [132]. They suggested that the porphyrin was protonated by the amberlyst-15 sulphonate groups and immobilised to the solid surface by electrostatic forces, rationalising the observed change in

• porphyrin colour from a purple powder to green when immobilised. The immobilisation of porphyrins onto polystyrene supports has been reported prior to this through covalent and electrostatic attractions but often suffered from poor coupling yields and low loadings [133][134][135][136]. Similarly, ionic

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

• Stephanie G. E. Amos,
• Marion Garreau,
• Luca Buzzetti and
• Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

• porphyrin [75] and rhodamine 6G (OD14) [76]. Aryl radicals from aryl halides. Aryl halides are generally more difficult to reduce than aryl diazonium salts (Ered < −1.2 V) [77][78]. However, they are more available and bench-stable. Their reduction potential is dependent on the substitution pattern and on

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• , 68502-100, Brazil 10.3762/bjoc.16.83 Abstract In this review we present relevant and recent applications of porphyrin derivatives as photocatalysts in organic synthesis, involving both single electron transfer (SET) and energy transfer (ET) mechanistic approaches. We demonstrate that these highly

• renewal of porphyrin applications in photocatalysis. Finally, the reaction scale in which the methodologies were developed are highlighted since this is an important parameter in the authors’ opinion. Keywords: energy transfer; photocatalysis; photooxygenation; photoredox; porphyrins; Introduction In

• continuous-flow photochemistry a sustainable alternative approach being applied already by the chemical and pharmaceutical industries. Porphyrinoid is the term given for a class of organic compounds containing four pyrrole rings connected by four methylene bridges, and include porphyrin, chlorin

Towards triptycene functionalization and triptycene-linked porphyrin arrays

• Gemma M. Locke,
• Keith J. Flanagan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2020, 16, 763–777, doi:10.3762/bjoc.16.70

• investigated for its use as a rigid isolating unit in the synthesis of multichromophoric arrays. Sonogashira cross-coupling conditions are utilized to attach various porphyrins and boron dipyrromethenes (BODIPYs) to the triptycene scaffold. While there are previous examples of triptycene porphyrin complexes

• , this work reports the first example of a linearly connected porphyrin dimer, linked through the bridgehead carbons of triptycene. Symmetric and unsymmetric examples of these complexes are demonstrated and single crystal X-ray analysis of an unsymmetrically substituted porphyrin dimer highlights the

• porphyrin units have been connected in a number of different ways; from phenylene, ethynyl, ethenyl or alkane linkers [5][6][7][8], to meso–β- [9] or β–β-linkages [10] or alternatively by connecting two or more meso–meso-linked porphyrin units via oxidative fusing reactions [11][12][13][14][15]. However

Fluorinated maleimide-substituted porphyrins and chlorins: synthesis and characterization

• Valentina A. Ol’shevskaya,
• Elena G. Kononova and
• Andrei V. Zaitsev

Beilstein J. Org. Chem. 2019, 15, 2704–2709, doi:10.3762/bjoc.15.263

• prepared based on the reaction of Zn(II) or Ni(II) complexes of 5,10,15,20-tetrakis(4-amino-2,3,5,6-tetrafluorophenyl)porphyrin and chlorin with maleic anhydride. Porphyrin maleimide derivatives were also prepared by the reaction of 5,10,15,20-tetrakis(4-azido-2,3,5,6-tetrafluorophenyl)porphyrinato Zn(II

• ) or Ni(II) with N-propargylmaleimide via the CuAAC click reaction to afford fluorinated porphyrin–triazole–maleimide conjugates. New maleimide derivatives were isolated in reasonable yields and identified by UV–vis, 1H NMR, 19F NMR spectroscopy and mass-spectrometry. Keywords: chlorin; maleimide

• ; porphyrin; spectral characteristics; synthesis; Introduction Porphyrins belong to a broad class of the natural and synthetic macroheterocyclic compounds with unique properties. They play an important role in photosynthesis [1], catalysis [2][3], nonlinear optics [4][5], polymer synthesis [6] and energy

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

• Groves [82] developed two manganese catalysts for the fluorination of C(sp3)–H bonds (Scheme 38). On the one hand, they employed a manganese porphyrin to catalyze the oxidative aliphatic C–H fluorination with iodosylbenzene (PhIO) as a stoichiometric oxidant. A variety of substrates, including simple

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• selectivity of this receptor for chloride anion is due to the cavity size (see Figure 3) [37]. 2.2. Optical anion sensing by 1,2,3-triazolium macrocycles within porphyrin cages Various porphyrin-based host supramolecules containing hydrogen-bond donor groups such as integrated amide, urea, pyrrole, ammonium

• and imidazolium which can recognize different anions, have been reported in the literature. As a matter of fact, porphyrin macrocycles are used for sensing of anionic compounds by a measurable physical response due to their intrinsic optical and redox properties [38]. Beer and co-workers have

• synthesized the novel tetra-1,2,3-triazolium zinc porphyrin cage 3 (Figure 4) and have probed its characteristics by using UV–visible spectroscopy, determining the association constants for complex formation in 5% water/acetone. This receptor has shown affinity toward all of the halide ions and especially

Introduction of an isoxazoline unit to the β-position of porphyrin via regioselective 1,3-dipolar cycloaddition reaction

• Xiujun Liu,
• Xiang Ma and
• Yaqing Feng

Beilstein J. Org. Chem. 2019, 15, 1434–1440, doi:10.3762/bjoc.15.143

• reaction trajectory, in which only the product with a link between the 5-position of the isoxazoline and the β-position of porphyrin was observed. The isoxazoline-porphyrins 3a,b have been characterized by absorption, emission, 1H NMR and mass spectra. Later, the crystal structure of 3a was obtained and

• ; isoxazoline; macrocycles; nitrile oxide; porphyrin; Introduction In nature, porphyrin-type compounds play a prominent role in life [1]. It is well known that certain vital functions, like O2 transport, photosynthesis etc. depend on the action of porphyrin–metal complexes [2][3][4][5]. Inspired by the natural

• [15][16][17][18][19][20][21][22][23][24]. Among them, the 1,3-dipolar cycloaddition reaction [25] is an efficient method to fuse five-membered rings on the periphery of the porphyrin framework. Because the periphery double bonds of the porphyrin macrocycle are nice dipolarophiles, and can trap 1,3

Selective detection of DABCO using a supramolecular interconversion as fluorescence reporter

• Indrajit Paul,
• Debabrata Samanta,
• Sudhakar Gaikwad and
• Michael Schmittel

Beilstein J. Org. Chem. 2019, 15, 1371–1378, doi:10.3762/bjoc.15.137

• -component rectangle [Cu4(1)2(2)2]4+ and the four-component sandwich complex [Cu2(1)(2)(4)]2+ is triggered by inclusion and release of DABCO (4). The fully reversible and clean switching between two multicomponent supramolecular architectures can be monitored by fluorescence changes at the zinc porphyrin

• sites. The structural changes are accompanied by a huge spatial contraction/expansion of the zinc porphyrin–zinc porphyrin distances that change from 31.2/38.8 Å to 6.6 Å and back. The supramolecular interconversion was used for the highly selective detection of DABCO in a mixture of other similar

• compounds. Keywords: copper; detection; fluorescence; interconversion; macrocycles; self-assembly; self-sorting; zinc porphyrin; Introduction Since dynamic multicomponent supramolecular structures are nowadays abundant [1][2], the weak intercomponent binding [3][4][5][6][7][8][9] is often instrumentalized

Extending mechanochemical porphyrin synthesis to bulkier aromatics: tetramesitylporphyrin

• Qiwen Su and
• Tamara D. Hamilton

Beilstein J. Org. Chem. 2019, 15, 1149–1153, doi:10.3762/bjoc.15.111

• -positions have been historically difficult in porphyrin synthesis, presumably owing to steric hindrance around the reactive site. We have used mechanochemistry for the simple, room-temperature synthesis of tetra-meso-substituted porphyrins. In the present study, mesitaldehyde undergoes acid-catalyzed

• mechanochemical condensation with pyrrole to give meso-tetrakis[2,4,6-(trimethyl)phenyl]porphyrin (TMP) after oxidation in solution. Yields are similar to those obtained using high-temperature porphyrin synthesis, although they remain significantly lower than some optimized room-temperature, solution-based

• , simple, room-temperature method for producing tetra-meso-substituted porphyrins with bulky substituents. Keywords: condensation; grinding; mechanochemistry; milling; porphyrin; sterically-hindered; Introduction Porphyrins and related macrocycles such as chlorins, corroles, and bacteriochlorins carry

Design, synthesis and spectroscopic properties of crown ether-capped dibenzotetraaza[14]annulenes

• Krzysztof M. Zwoliński and
• Julita Eilmes

Beilstein J. Org. Chem. 2019, 15, 617–622, doi:10.3762/bjoc.15.57

• techniques and apparatuses [11]. Particularly, the crown ether-capped (or ‘crown-capped’) porphyrins are synthesized conventionally under high-dilution conditions starting from two porphyrin building blocks bearing complementary functionalities, such as amine and either acyl chloride [12] or halomethyl [13

• partially overlapped with proton resonances of aliphatic bridges. Receptor 3b displays the properties of chemical shift reagents, similar to the previously reported crown ether-capped porphyrin [36] but of different origin. Since, the macrocyclic dibenzotetraaza[14]annulene core is antiaromatic, and shows

Learning from B₁₂ enzymes: biomimetic and bioinspired catalysts for eco-friendly organic synthesis

• Keishiro Tahara,
• Ling Pan,
• Toshikazu Ono and
• Yoshio Hisaeda

Beilstein J. Org. Chem. 2018, 14, 2553–2567, doi:10.3762/bjoc.14.232

• ligands of cobalt complexes 2 are superior to porphyrin ligands in terms of the model for the corrin framework of B12; both the imine/oxime-type and corrin ligands are monoanionic [57][58][59][60]. The imine/oxime-type cobalt complex 2 can be isolated in both the monoalkylated and dialkylated forms [59

Synthesis and characterization of π–extended “earring” subporphyrins

• Haiyan Guan,
• Mingbo Zhou,
• Bangshao Yin,
• Ling Xu and
• Jianxin Song

Beilstein J. Org. Chem. 2018, 14, 1956–1960, doi:10.3762/bjoc.14.170

• antiaromatic character of the ear-containing macrocycle, which is quite similar to the analogous “earring” porphyrin [38]. Furthermore, the antiaromaticity of the ear-containing macrocycle is proved by the large positive NICS value in the hole as well as the anticlockwise ring currency (see Supporting

• Information File 1 for details). Although some characteristic peaks in the 1H NMR spectrum of the “earring” subporphyrin are quite similar to those of “earring” porphyrin, there are some differences in their structures. This is mainly due to the fact that the bowl-shaped subporphyrin core differs

• significantly from the saddle-shaped or nearly planar porphyrin core. To elucidate the differences in their structures, we endeavored to cultivate single crystals of 3 and collected the data. The diffraction data unambiguously confirmed the designated structure (Figure 2) and revealed that all peripheral C–C

Recent advances in phosphorescent platinum complexes for organic light-emitting diodes

• Cristina Cebrián and
• Matteo Mauro

Beilstein J. Org. Chem. 2018, 14, 1459–1481, doi:10.3762/bjoc.14.124

• including photocatalysis [6], bio-imaging [7][8], and solar-energy conversion [9], just to cite a few. Thompson and Forrest reported in 1998 on the first example of a phosphorescent emitter, namely 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (Pt(OEP)), used as dopant for the fabrication of

Synthesis and spectroscopic properties of β-meso directly linked porphyrin–corrole hybrid compounds

• Baris Temelli and
• Hilal Kalkan

Beilstein J. Org. Chem. 2018, 14, 187–193, doi:10.3762/bjoc.14.13

• Baris Temelli Hilal Kalkan Hacettepe University, Department of Chemistry, Beytepe Campus, 06800, Ankara, Turkey 10.3762/bjoc.14.13 Abstract The preparation of β-meso directly linked porphyrin–corrole hybrids was realized for the first time via an InCl3-catalyzed condensation reaction of 2-formyl

• -5,10,15,20-tetraphenylporphyrins with meso-substituted dipyrromethanes. Hybrid compounds have been characterized by 1H NMR, 13C NMR, 2D NMR, UV–vis absorption and fluorescence spectroscopy. Keywords: corrole; hybrid compounds; indium(III) chloride; porphyrin; porphyrinoids; Introduction Porphyrins and

• metalloporphyrins play an important role in chemistry, biology, medical and materials sciences because of their presence in biological compounds such as chlorophyll and heme molecules that have very important functions in the metabolism of living organisms [1][2]. In recent years, efforts in porphyrin chemistry

Synthesis and application of trifluoroethoxy-substituted phthalocyanines and subphthalocyanines

• Satoru Mori and
• Norio Shibata

Beilstein J. Org. Chem. 2017, 13, 2273–2296, doi:10.3762/bjoc.13.224

• . Keywords: aggregation; fluorine; phthalocyanine; subphthalocyanine; trifluoroethoxy; Introduction Phthalocyanines [1][2][3] are analogues of porphyrin condensed with four isoindoline units via a nitrogen atom and exhibit a deep blue color due to their wide 18π electron conjugation. Among them, the most

• based on their unique functions. Phthalocyanines are also expected to be applied as functional dyes. A series of compounds having a macrocyclic π-conjugated system including porphyrin are known as functional dyes. In particular, phthalocyanines have a wide range of functions and are expected to serve as

Phosphonic acid: preparation and applications

• Charlotte M. Sevrain,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2017, 13, 2186–2213, doi:10.3762/bjoc.13.219

• metal affinity chromatography (IMAC). Such types of solid phases were applied to enrich carbohydrate from extracts [61] or as chiral selectors immobilized on silica for chiral cation exchange chromatography [62] (Figure 4). Porphyrin tetra-functionalized with phosphonic acid groups was used as a

Direct catalytic arylation of heteroarenes with meso-bromophenyl-substituted porphyrins

• Alexei N. Kiselev,
• Olga K. Grigorova,
• Alexei D. Averin,
• Sergei A. Syrbu,
• Oskar I. Koifman and
• Irina P. Beletskaya

Beilstein J. Org. Chem. 2017, 13, 1524–1532, doi:10.3762/bjoc.13.152

• fields of modern organic chemistry due to their unique structure and electronic properties. These molecules have already proved to be powerful tools in phototherapy, radioimmunotherapy and imaging [1], for cancer treatment [2], and actually sophisticated theranostic porphyrin-based nanodevices have been

• application of such medicaments are antitumor remedies and non-invasive diagnostic imaging agents for PET, SPECT and MRI methods [5]. The combination of porphyrin and heterocyclic moieties in one molecule is perspective for the design of new compounds with potential powerful pharmaceutical properties. Up to

• the use of dioxane instead of DMF and the decrease in the reaction temperature down to 100 °C, did not notably change the yield of 3 (34%, Table 1, entry 3). The use of porphyrin in excess diminished the yield (Table 1, entry 4). The reaction of benzoxazole with a more acidic C–H bond resulted in a

Novel β-cyclodextrin–eosin conjugates

• Gábor Benkovics,
• Damien Afonso,
• András Darcsi,
• Szabolcs Béni,
• Sabrina Conoci,
• Éva Fenyvesi,
• Lajos Szente,
• Milo Malanga and
• Salvatore Sortino

Beilstein J. Org. Chem. 2017, 13, 543–551, doi:10.3762/bjoc.13.52

• diffuses in the cellular environment over short distances (few tens of nm) resulting in negligible systemic side effects. For PDT applications CDs have been conjugated with porphyrin [7] and protoporphyrin (5-aminolevulinic acid) [8] in order to enhance the membrane penetration of the PS (or its prodrug

• systems in combined phototherapies. This approach has recently led to self-assembled systems based on a porphyrin–β-CD conjugate and a tailored nitric oxide photoreleaser forming a strong inclusion complex with the β-CD cavity [9]. This supramolecular nanoassembly simultaneously releases cytotoxic 1O2 and

• nitric oxide under illumination with visible light, resulting in amplified cancer-cell mortality [9]. By attaching porphyrin to γ-CD and dimeric β-CD, which are both able to form inclusion complexes with cytotoxic drug molecules such as doxorubicin and paclitaxel, nanocarriers with multimodal therapeutic

Efficient access to β-vinylporphyrin derivatives via palladium cross coupling of β-bromoporphyrins with N-tosylhydrazones

• Vinicius R. Campos,
• Ana T. P. C. Gomes,
• Anna C. Cunha,
• Maria da Graça P. M. S. Neves,
• Vitor F. Ferreira and
• José A. S. Cavaleiro

Beilstein J. Org. Chem. 2017, 13, 195–202, doi:10.3762/bjoc.13.22

• such synthetic methodology in porphyrin chemistry allowing the synthesis of new derivatives, containing β-arylvinyl substituents. Keywords: N-tosylhydrazones; Pd-catalyzed cross coupling; porphyrins; Introduction Porphyrin-type heterocycles are well known for their special role in several scientific

• diversity of structural features that can be induced in the porphyrin structure [14][15][16]. Alkenyl-type moieties are examples of versatile functional groups which are present in several biologically active natural porphyrin derivatives or are substituents that can be introduced into the macrocycles

• , affording in such way important intermediates for different synthetic strategies [4][17][18]. There are methods available allowing the insertion of alkenyl groups into porphyrin macrocycles (e.g., Heck reaction [4], metathesis [7][19][20][21], Wittig reaction [22][23]). However, palladium-catalyzed cross

Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates

• Mohammad Haji

Beilstein J. Org. Chem. 2016, 12, 1269–1301, doi:10.3762/bjoc.12.121

• to create three intermolecular bonds. A ruthenium–porphyrin complex-catalyzed three-component reaction of α-diazophosphonates 180, nitrosoarenes 181, and alkynes 182 to give multifunctionalized aziridinylphosphonates 183 has been reported by Reddy et al. (Scheme 39) [77]. The desired

• conditions. CuI-catalyzed four-component reactions of methyleneaziridines towards alkylphosphonates. Ruthenium–porphyrin complex-catalyzed three-component synthesis of aziridinylphosphonates and its proposed mechanism. Copper(I)-catalyzed three-component reaction towards 1,2,3-triazolyl-5-phosphonates. Three