Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• /22 ratio of 1:2, which revealed that the singlet spin-state of coumarin could be involved in the photodimerization process within the CB[8] cavity and that the triplet state could be shielded from external quenchers (O2 as a triplet quencher). These results also indicated that photodimerization could

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

• . Photoisomerization of the azo unit between cis and trans is achieved upon irradiation with 505 nm (trans→cis) and 435 nm (cis→trans). Concurrently with the isomerization and coordination/decoordination, the spin state of the Ni ion switches between singlet (low-spin) and triplet (high-spin). Previous studies have

• )-porphyrins; photoswitch; record player molecules; spin state; spin switch; Introduction Molecular spin switches operated with visible light in homogeneous solution [1] or on surfaces [2], hold promise for a number of hitherto unprecedented applications such as switchable contrast agents [3][4][5][6][7

• ) nitrogen (“needle”) is placed onto the Ni ion. The coordination number of the Ni2+ ion changes from 4 (square planar) to 5 (square pyramidal) and concomitantly, the spin state changes from low-spin (singlet, diamagnetic) to high-spin (triplet, paramagnetic). Previous studies have shown that all three

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

• + ion. Light of 435 nm (violet) isomerizes the ligand back to the trans configuration, which decoordinates for steric reasons. This so-called record player design has been used previously to switch the spin state of Ni2+ between singlet and triplet. We now use the coordination/decoordination process to

Experimental and computational electrochemistry of quinazolinespirohexadienone molecular switches – differential electrochromic vs photochromic behavior

• Eric W. Webb,
• Jonathan P. Moerdyk,
• Kyndra B. Sluiter,
• Benjamin J. Pollock,
• Amy L. Speelman,
• Eugene J. Lynch,
• William F. Polik and
• Jason G. Gillmore

Beilstein J. Org. Chem. 2019, 15, 2473–2485, doi:10.3762/bjoc.15.240

• likely be the first singlet excited state (S1), T0 and S1 possess equivalent orbital occupancy and differ only in their spin state. Our rationale for using T0 rather than S1 is that ignoring electron-exchange interaction introduces substantially less error than using different computational methods when

Solvent-free copper-catalyzed click chemistry for the synthesis of N-heterocyclic hybrids based on quinoline and 1,2,3-triazole

• Martina Tireli,
• Silvija Maračić,
• Stipe Lukin,
• Marina Juribašić Kulcsár,
• Dijana Žilić,
• Mario Cetina,
• Ivan Halasz,
• Silvana Raić-Malić and
• Krunoslav Užarević

Beilstein J. Org. Chem. 2017, 13, 2352–2363, doi:10.3762/bjoc.13.232

• -free click reactions. Electron spin resonance (ESR) spectroscopy ESR is an ideal technique for validating the oxidation and spin state of copper cations. Elemental copper and copper(I) are ESR silent, whereas the copper(II) shows strong and characteristic lines revealing local properties of this ion

Biochemical and structural characterisation of the second oxidative crosslinking step during the biosynthesis of the glycopeptide antibiotic A47934

• Veronika Ulrich,
• Clara Brieke and
• Max J. Cryle

Beilstein J. Org. Chem. 2016, 12, 2849–2864, doi:10.3762/bjoc.12.284

• in the low-spin state, indicating the heme moiety of StaF to be present in its water-bound ferric form. Equivalent spectra were observed for related P450s such as StaH, OxyAtei, OxyBtei and OxyEtei, which are also involved in GPA cyclisation reactions [12][14][19][22]. Reduction of StaF by addition

On the cause of low thermal stability of ethyl halodiazoacetates

• Magnus Mortén,
• Martin Hennum and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2016, 12, 1590–1597, doi:10.3762/bjoc.12.155

• obtain an energy difference between the singlet and triplet electronic spin state (Figure 3). The singlet–triplet energy gap is 4.1 kcal/mol in favor of the triplet state for the EDA-generated carbene. All three carbenes generated from 2a–c on the other hand have singlet ground states. The singlet

Tuning the interactions between electron spins in fullerene-based triad systems

• Maria A. Lebedeva,
• Thomas W. Chamberlain,
• E. Stephen Davies,
• Bradley E. Thomas,
• Martin Schröder and
• Andrei N. Khlobystov

Beilstein J. Org. Chem. 2014, 10, 332–343, doi:10.3762/bjoc.10.31

• six electrons per fullerene cage to form species containing one or more unpaired electrons, in which overall charge and the spin state can be controlled precisely by applied potential [9]. In addition, combining two fullerene cages within the same molecule increases the total spin-carrying capacity

High-spin intermediates of the photolysis of 2,4,6-triazido-3-chloro-5-fluoropyridine

• Sergei V. Chapyshev,
• Denis V. Korchagin,
• Patrik Neuhaus and
• Wolfram Sander

Beilstein J. Org. Chem. 2013, 9, 733–742, doi:10.3762/bjoc.9.83

• safely assigned to trinitrene 18 since only this trinitrene has a septet spin state. According to EPR spectral simulations (Figure 1a), this trinitrene is formed in ca. 2% yield. Due to different substituents in positions 3 and 5 of the pyridine ring, trinitrene 18 has different angles Θ1, Θ2, Θ3 between

Spin state switching in iron coordination compounds

• Philipp Gütlich,
• Ana B. Gaspar and
• Yann Garcia

Beilstein J. Org. Chem. 2013, 9, 342–391, doi:10.3762/bjoc.9.39

• pressure sensors as well as optical devices. The article begins with a brief description of the principle of molecular spin state switching using simple concepts of ligand field theory. Conditions to be fulfilled in order to observe spin crossover will be explained and general remarks regarding the

• ; polyfunctional materials; spin crossover; Introduction Coordination compounds of transition-metal ions may, under certain conditions, exhibit a switching phenomenon, whereby the central metal ion changes the spin state upon a change of temperature, application of pressure, irradiation with light, or in a

• magnetic field. This phenomenon is known as spin transition (ST) or spin crossover (SCO). The change of spin state is accompanied by a change of electronic structure of the central ion and the complex molecule on the whole, which changes markedly the physical and chemical properties of the substance. Most

The arene–alkene photocycloaddition

• Ursula Streit and
• Christian G. Bochet

Beilstein J. Org. Chem. 2011, 7, 525–542, doi:10.3762/bjoc.7.61

• that such cycloadditions can take place from the S1 excited-state without barrier through a conical intersection, which is common to all three cycloadducts [21], at least for the benzene/ethylene system. Quenching and sensitizing experiments were carried out to elucidate the spin state of the excited

Prediction of reduction potentials from calculated electron affinities for metal-salen compounds

• Sarah B. Bateni,
• Kellie R. England,
• Anthony T. Galatti,
• Handeep Kaur,
• Victor A. Mendiola,
• Alexander R. Mitchell,
• Michael H. Vu,
• Benjamin F. Gherman and
• James A. Miranda

Beilstein J. Org. Chem. 2009, 5, No. 82, doi:10.3762/bjoc.5.82

• EA, B97-1 was determined to be the optimal functional for reproducing both key geometric and electronic features of the metal-salens. Among the metal-salens considered in the training and test sets, only one possible spin state need be considered for the neutral and reduced forms of the Cu(II

• ) (doublet and singlet, respectively) and Zn(II) (singlet and doublet, respectively) salens. For the complexes including Ni(II) and Pd(II), the ground state of the neutral form was in all cases found to be the singlet spin state, while only the doublet state is possible for the one-electron reduced forms