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The electronic structures and, particularly, the nature of the HOMO in a series of PcFeL2, PcFeL'L″, and [PcFeX2]2- complexes (Pc = phthalocyaninato(2-) ligand; L = NH3, n-BuNH2, imidazole (Im), pyridine (Py), PMe3, PBu3, t-BuNC, P(OBu)3, and DMSO; L' = CO; L″ = NH3 or n-BuNH2; X = NCO-, NCS-, CN-, imidazolate (Im-), or 1,2,4-triazolate(Tz-)) were probed by electrochemical, spectroelectrochemical, and chemical oxidation as well as theoretical (density functional theory, DFT) studies. In general, energies of the metal-centered occupied orbitals in various six-coordinate iron phthalocyanine complexes correlate well with Lever Electrochemical Parameter EL and intercross the phthalocyanine-centered a1u orbital in several compounds with moderate-to-strong π-accepting axial ligands. In these cases, an oxidation of the phthalocyanine macrocycle (Pc(2-)/Pc(1-)) rather than the central metal ion (Fe(II)/Fe(III)) was theoretically predicted and experimentally confirmed.

The reaction of diiminoisoindoline and iminoxoisoindoline with aminoazoles results in the formation of bidentate chelates that can be considered a semihemiporphyrazine. These chelates react with BF3 to produce fluorescent compounds that are structurally analogous to the BODIPY dyes. These difluoroboron semihemiporphyrazines (BOSHPYs) aggregate, and the type of aggregation (H or J) is determined by a single atom at the periphery of the ligand (O or N). Notably, the imine terminated compounds remain fluorescent upon aggregation.

The electronic structure, redox properties, and long-range metal-metal coupling in metal-free 5,10,15,20-tetra(ruthenocenyl)porphyrin (H2TRcP) were probed by spectroscopic (NMR, UV-vis, magnetic circular dichroism (MCD), and atmospheric pressure chemical ionization (APCI)), electrochemical (cyclic voltammetry, CV, and differential pulse voltammetry, DPV), spectroelectrochemical, and chemical oxidation methods, as well as theoretical (density functional theory, DFT, and time-dependent DFT, TDDFT) approaches. It was demonstrated that the spectroscopic properties of H2TRcP are significantly different from those in H2TFcP (metal-free 5,10,15,20-tetra(ferrocenyl)porphyrin). Ruthenocenyl fragments in H2TRcP have higher oxidation potentials than the ferrocene groups in the H2TFcP complex. Similar to H2TFcP, we were able to access and spectroscopically characterize the one- and two-electron oxidized mixed-valence states in the H2TRcP system. DFT predicts that the porphyrin π-system stabilizes the [H2TRcP]+ mixed-valence cation and prevents its dimerization, which is characteristic for ruthenocenyl systems. However, formation of the mixed-valence [H2TRcP]2+ is significantly less reproducible than the formation of [H2TRcP]+. DFT and TDDFT calculations suggest the ruthenocenyl fragment dominance in the highest occupied molecular orbital (HOMO) energy region and the presence of the low-energy MLCT (Rc → porphyrin (π*)) transitions in the visible region with energies higher than the predominantly porphyrin-centered Q-bands.

A one-step synthetic pathway for the preparation of fully conjugated β-isoindigo-azaDIPY hybrid chromophores comprised of β-isoindigo and azadipyrromethene moieties is reported. The target compounds were characterized by spectroscopic, crystallographic, and theoretical methods and show unprecedented broad absorption across the visible region of the electromagnetic spectrum. The X-ray crystal structure of the octa(n-butyl)-β-isoindigo-azaDIPY derivative revealed that a trans-configuration of the β-isoindigo fragment accompanies a planar conjugated core.

A one-step, gram-scale protocol for the preparation of 1-imino-3-thioisoindolines and a novel one-pot two-step methodology of the synthesis of dithio- or diamino-β-isoindigo derivatives starting from phthalonitriles and sodium hydrosulfide in an aprotic dipolar solvent have been developed. It was demonstrated that the electronic properties of the substituent(s) in the phthalonitrile core play a critical role in β-isoindigo synthesis resulting either in the selective formation of dithio- or diamino-β-isoindigo chromophores. The

The electronic communication between two ferrocene groups in the electron-deficient expanded aza-BODIPY analogue of zinc manitoba-dipyrromethene (MB-DIPY) was probed by spectroscopic, electrochemical, spectroelectrochemical, and theoretical methods. The excited-state dynamics involved sub-ps formation of the charge-separated state in the organometallic zinc MB-DIPYs, followed by recovery of the ground state via charge recombination in 12 ps. The excited-state behavior was contrasted with that observed in the parent complex that lacked the ferrocene electron donors and has a much longer excited-state lifetime (670 ps for the singlet state). Much longer decay times observed for the parent complex without ferrocene confirm that the main quenching mechanism in the ferrocene-containing 4 is reflective of the ultrafast ferrocene-to-MB-DIPY core charge transfer (CT).

A series of PtII-based monometallic (H2PtL), homobimetallic (Pt2L), and heterobimetallic (NiPtL and PdPtL) group 10 complexes of the previously established expanded twin porphyrin (H4L) were prepared. Structural characterization of the bimetallic PtII series (Pt2L, NiPtL, and PdPtL) revealed their similar general structures, with slight differences correlated to the ion size. An improvement of the metal-ion insertion process also allowed efficient preparation of the known Pd2L complex, and the novel heterobimetallic NiPdL complex was also structurally characterized. UV-vis spectroscopy, NMR spectroscopy, magnetic circular dichroism (MCD), and (spectro)electrochemistry were used to characterize the complexes; the electronic properties followed largely established lines for metal complexes of the twin porphyrin, except that the PtII-based systems exhibited more complex UV-vis spectral signatures. MCD spectra accompanied by density functional theory (DFT)/time-dependent DFT computations (TDDFT) rationalize the origins of the optical features of the twin porphyrin. The presence of the nonplanar, nonaromatic macrocyclic π system with conjugation pathways confined to each half of the molecule could be visualized. Significant pyrazole(π) → pyrrole(π*) charge-transfer character was predicted for several transitions in the visible region. This study adds to our fundamental understanding of the formation, structure, and electronic structure of bimetallic complexes of this class of expanded metalloporphyrins containing nonpyrrolic moieties.

The chemically or spectroelectrochemically generated formation and aggregation of zinc(II) tetra-tert-butylphthalocyanine cation radical [ZnPctBu]+•, which was highly soluble in common organic solvents, were investigated using UV-vis and magnetic circular dichroism (MCD) spectroscopies with an emphasis on the influence of the axial ligand on the fingerprint (∼500 nm) and NIR (720∼1000 nm) spectral envelopes. MCD spectroscopy is suggestive that the NIR band at ∼1000 nm observed for the antiferromagnetically coupled cation radical dimer, [ZnPctBu]22+, has no degeneracy, the monomer-dimeric equilibrium is temperature dependent, and higher degree aggregates can be formed at specific conditions. Sixteen different exchange-correlation functionals were tested to accurately predict the energies, intensities, and profiles of the UV-vis and MCD spectra of the phthalocyanine cation radical monomer and dimer. It was found that the M05 exchange-correlation functional (along with several other functionals that include 27-42% of Hartree-Fock exchange) provided an excellent agreement (∼0.1 eV for the degenerate excited states observed by MCD spectroscopy) between theory and experiment for the phthalocyanine cation-radical monomer and dimer. Not only did time-dependent density functional theory (TDDFT) calculations with M05 exchange-correlation functional correctly predict the nondegenerate NIR charge-transfer band at ∼1000 nm, all degenerate excited states, monomer and dimer energies, and oscillator strengths, but also they correctly described the nature of the experimentally observed at ∼500 nm MCD B-term (fingerprint band) detected for both the monomeric and dimeric phthalocyanine cation radicals. The TDDFT data explain the similarities in the UV-vis and MCD spectra of the monomeric and dimeric species observed between the UV and fingerprint spectral envelopes as well as correctly predicted the antiferromagnetic coupling between the two singly oxidized phthalocyanine macrocycles in the dimer.

We developed a simple methodology for the preparation of stable meso-(nitrile oxide)-substituted BODIPYs, which were characterized by spectroscopic methods and X-ray crystallography. These compound...

Two isomeric ruthenium(II)/5,10,15,20-tetraphe-nylporphyrin complexes featuring axially coordinated redox-active, low-optical gap 2- or 6-isocyanoazulene ligands have been isolated and characterized by NMR, UV-vis, and magnetic circular dichroism (MCD) spectroscopic methods, high-resolution mass spectrometry, and single-crystal X-ray crystallography. The UV-vis and MCD spectra support the presence of the low-energy, azulene-centered transitions in the Q band region of the porphyrin chromophore. The first coordination sphere in new L2RuTPP complexes reflects compressed tetragonal geometry. The redox properties of the new compounds were assessed by electrochemical and spectroelectrochemical means and correlated with the electronic structures predicted by density functional theory and CASSCF calculations. Both experimental and theoretical data are consistent with the first two reduction processes involving the axial azulenic ligands, whereas the oxidation profile (in the direction of increasing potential) is exerted by the ruthenium ion, the porphyrin core, and the axial azulenic moieties.

A series of covalent ferrocene-BODIPY-fullerene triads with the ferrocene groups conjugated to the BODIPY π-system and the fullerene acceptor linked at the boron hub by a common catecholpyrrolidine bridge were prepared and characterized by 1D and 2D NMR, UV/Vis, steady-state fluorescence spectroscopy, high-resolution mass spectrometry, and, for one of the derivatives, X-ray crystallography. Redox processes of the new compounds were investigated by electrochemical (CV and DPV) methods and spectroelectrochemistry. DFT calculations indicate that the HOMO in all triads was delocalized between ferrocene and BODIPY π-system, the LUMO was always fullerene-centered, and the catechol-centered occupied orbital was close in energy to the HOMO. TDDFT calculations were indicative of the low-energy, low-intensity charge-transfer bands originated from the ferrocene-BODIPY core to fullerene excitation, which explained the similarity of the UV/Vis spectra of the ferrocene-BODIPY dyads and ferrocene-BODIPY-fullerene triads. Photophysical properties of the new triads as well as reference BODIPY-fullerene and ferrocene-BODIPY dyads were investigated by pump-probe spectroscopy in the UV/Vis and NIR spectral regions following selective excitation of the BODIPY-based antenna. Initial charge transfer from the ferrocene to the BODIPY core was shown to outcompete sub-100 fs deactivation of the excited state mediated by the catechol bridge. However, no subsequent electron transfer to the fullerene acceptor was observed. The initial charge separated state relaxes by recombination with a time constant of 150-380 ps.

A series of a fully conjugated ferrocene-containing coumarins and B,O-chelated coumarins was prepared and characterized by a variety of spectroscopic (UV–vis, NMR, and mass spectrometry), electrochemical (CV and DPV) and spectroelectrochemical methods. The photophysical properties of the target compounds were investigated by steady-state fluorescence and ultrafast transient absorption spectroscopy methods. Selective photoexcitation of the coumarin core was followed by ultrafast electron transfer from the ferrocene fragment, resulting in formation of a charge-separated Fc+-coumarin-. state. This charge-separated state undergoes ultrafast ground state recovery in 20–25 ps, shortening the excited state lifetime of the organic coumarin precursors (1.2–1.5 ns) by almost two orders of magnitude. Formation of the charge-separated states was supported by the experimental (steady-state fluorescence oxidative titrations) and theoretical DFT and TDDFT calculations.

A ditriflate derivative of 2-iodoxybenzoic acid (IBX) was prepared by the reaction of IBX with trifluoromethanesulfonic acid and characterized by single crystal X-ray crystallography. IBX-ditriflate is the most powerful oxidant in a series of structurally similar IBX derivatives which is best illustrated by its ability to readily oxidize hydrocarbons and the oxidation resistant polyfluoroalcohols.

The ability of density functional theory (DFT) and time-dependent DFT (TDDFT) methods for the accurate prediction of the energies and oscillator strengths of the excited states in a series of fully conjugated meso-meso β-β β-β triple-linked porphyrin oligomers (porphyrin tapes 2-12) was probed in the gas phase and solution using several exchange-correlation functionals. It was demonstrated that the use of the hybrid B3LYP functional provides a good compromise for the accurate prediction of the localized π-π* and intramolecular charge-transfer transitions, thus allowing confident interpretation of the UV-vis-NIR spectra of porphyrin oligomers. The TDDFT-based sum-over-state (SOS) calculations for the porphyrin tape dimer 2 and trimer 3 as well as parent monomer 1 correctly predicted the signs and shapes of the magnetic circular dichroism (MCD) signals in the low-energy region of the spectra.

Density Functional Theory (DFT) calculations coupled with several exchange-correlation functionals were used for the prediction of Mossbauer hyperfine parameters of 36 bis-axially coordinated iron(II) phthalocyanine complexes with the general formulas PcFeL2, PcFeL'L″, and [PcFeX2]2-, including four new compounds. Both gas-phase and PCM calculations using BPW91 and MN12L exchange-correlation functionals were found to accurately predict both Mossbauer quadrupole splittings and the correct trends in experimentally observed isomer shifts. In comparison, hybrid exchange-correlation functionals underestimated quadrupole splittings, while still accurately predicted isomer shifts. Out of ∼40 exchange-correlation functionals tested, only MN12L was found to correctly reproduce quadrupole splitting trends in the PcFeL2 complexes coordinated with phosphorus-donor axial ligands (i.e., P(OnBu)3 ≈ P(OEt)3 < PMe3 < P[(CH2O)2CH2]-p-C6H4NO2 < PEt3 ≈ PnBu3). Natural Bond Orbital (NBO) analysis was successfully used to explain the general trends in the observed quadrupole splitting for all compounds of interest. In particular, the general trends in the quadrupole splitting correlate well with the axial ligand dependent, NBO-predicted population of the 3dz2 orbital of the Fe ion and are reflective of the hypothesis proposed by Ohya and co-workers ( Inorg. Chem., 1984, 23, 1303) on the adaptability of the phthalocyanine's π-system toward Fe-Lax interactions. The first X-ray crystal structure of a PcFeL2 complex with axial phosphine ligands is also reported.

The direct borylation of two bis(pyrazolylimino)isoindoline chelates with BF3 and base under dry conditions results in the formation of two boron adducts. These are ring-contracted analogs of biliazine and can be considered as subbiliazines, as they have bowl-shaped structures similar to subphthalocyanine. Additionally, a new iminooxoisoindoline BF2 complex was made from hydrolysis of the free base in the presence ofBF3. The electronic structures of the free bases and subbiliazines were probed by density functional theory (DFT) and time-dependent DFT (TDDFT) methods.

Several pyrene-boron-dipyrromethene (BODIPY) and pyrene-BODIPY-ferrocene derivatives with a fully conjugated pyrene fragment appended to the α-position(s) of the BODIPY core have been prepared by Knoevenagel condensation reaction and characterized by one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR), UV-vis, fluorescence spectroscopy, high-resolution mass spectrometry as well as X-ray crystallography. The redox properties of new donor-acceptor BODIPY dyads and triads were studied by electrochemical (cyclic voltammetry (CV) and differential pulse voltammetry (DPV)) and spectroelectrochemical approaches. Formation of weakly bonded noncovalent complexes between the new pyrene-BODIPYs and nanocarbon materials (C60, C70, single-walled carbon nanotube (SWCNT), and graphene) was studied by UV-vis, steady-state fluorescent, and time-resolved transient absorption spectroscopy. UV-vis and fluorescent spectroscopy are indicative of the much stronger and selective interaction between new dyes and (6,5)-SWCNT as well as graphene compared to that of C60 and C70 fullerenes. In agreement with these data, transient absorption spectroscopy provided no evidence for any significant change in excited-state lifetime or photoinduced charge transfer between pyrene-BODIPYs and C60 or C70 fullerenes when the pyrene-BODIPY chromophores were excited into the lowest-energy singlet excited state. Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations suggest that the pyrene fragments are fully conjugated into the π-system of BODIPY core, which correlates well with the experimental data.

An insight into the electronic structure of the metal-free, unsubstituted, and nonperipherally substituted with electron-donating groups tetraazaporphyrin (H2TAP), phthalocyanine (H2Pc), naphthalocyanine (H2Nc), anthracocyanine (H2Ac) platforms has been gained and discussed on the basis of experimental UV-vis and MCD spectra as well as density functional theory (DFT), time-dependent DFT (TDDFT), and semiempirical ZINDO/S calculations. Experimental data are suggestive of potential crossover behavior between the 1 1B2u and 1 1B3u excited states (in traditional D2h notation) around 800 nm. A large array of exchange-correlation functionals were tested to predict the vertical excitation energies in H2TAPs, H2Pcs, H2Ncs, and H2Acs both in gas phase and solution. In general, TDDFT-predicted energies of the Q x and Q y bands and the splitting between them correlate well with the amount of Hartree-Fock exchange present in a specific exchange-correlation functional with the long-range corrected LC-BP86 and LC-wPBE functionals providing the best agreement between theory and experiment. The pure GGA (BP86) exchange-correlation functional significantly underestimated, while long-range corrected LC-BP86 and LC-wPBE exchange-correlation functionals and semiempirical ZINDO/S method strongly overestimated the intramolecular charge-transfer (ICT) transitions experimentally observed for -OR, -SR, and -NR2 substituted at nonperipheral position phthalocyanines and their analogues in the 450-650 nm region. The hybrid CAM-B3LYP, PBE1PBE, and B3LYP exchange-correlation functionals were found to be much better in predicting energies of such ICT transitions. Overall, we did not find a single exchange-correlation functional that can accurately (MAD < 0.05 eV) and simultaneously predict the energies and the splittings of the Q x and Q y bands as well as energies of the ICT transitions in a large array of substituted and unsubstituted metal-free phthalocyanines and their benzoannulated analogues.

A series of 1,7-dipyrene-aza-BODIPY and 1,7-dipyrene-3,5-diferrocene-aza-BODIPY derivatives 5a–e with pyrene ligands covalently attached to the β-pyrrolic positions of the boron-azadipyrromethene (...

Three water-soluble quaternized metal-free tetra-(3-pyridyl)bacteriochlorins were synthesized and characterized by UV-vis, MCD, and NMR spectroscopy as well as elemental analysis. DFT calculations are indicative of the [Formula: see text]HOMO [Formula: see text] [Formula: see text]LUMO relationship, which correlates well with the experimentally observed by MCD spectroscopy for all bacteriochlorins “reversed” sign sequence in the Vis-NIR region. TDDFT calculations also correctly predict large splitting between the [Formula: see text] and [Formula: see text] bands as well as splitting of the Soret band observed experimentally in all bacteriochlorins.

A new aza-BODIPY-hydrazone-based fluorescence probe with red-emission for selective detection of HClO was synthesized and characterized using 1H and 13C NMR, IR, and HRMS. The probe demonstrated a fast, red fluorescence response in the detection of HClO. The sensing mechanism originated from the imine C N bond cleavage by HClO which resulted in the formation of a fluorescent aza-BODIPY aldehyde. The probe showed low toxicity to living cells and the fluorescence imaging experiments in living RAW264.7 cells showed intracellular red fluorescence developed when NaClO and PMA were incubated with the probe, suggesting its potential application for the detection of exogenous and endogenous HClO in living cells. Reactive oxygen and nitrogen species do not interfere with activation of a new fluorescence probe.

The asymmetric unit of the title compound {systematic name: 3-[(tert-butyldiphenylsilyl)oxy]propane-1,2-diol, C19H26O3Si}, contains eight chiral molecules (Z′ = 8). These molecules are connected via a complex system of hydrogen bonds into an infinite assembly along the [100] axis; hydrophobic tert-butyl and phenyl groups form an external coating of the assembly. These assemblies are packed by weak intermolecular interactions in a peculiar formation resembling a `header bond' masonry brick wall. Disorder of flexible fragments increases with temperature but the same crystal structure exists from 120 to 220 K (and most probably to the melting point at 334 K).

The selective preparation of 2-iodoxybenzenesulfonic acid (IBS, as potassium or sodium salts) by oxidation of sodium 2-iodobenzenesulfonate with Oxone or sodium periodate in water is reported. The single crystal X-ray diffraction analysis reveals a complex polymeric structure consisting of three units of IBS as potassium salt and one unit of 2-iodoxybenzenesulfonic acid linked together by relatively strong I=O···I intermolecular interactions. Furthermore, a new method for the preparation of the reduced form of IBS, 2-iodosylbenzenesulfonic acid, by using periodic acid as an oxidant, has been developed. It has been demonstrated that the oxidation of free 2-iodobenzenesulfonic acid under acidic conditions affords an iodine(III) heterocycle (2-iodosylbenzenesulfonic acid), while the oxidation of sodium 2-iodobenzenesulfonate in neutral aqueous solution gives the iodine(V) products.

A two-step synthetic pathway for direct introduction of the nitromethyl functional group at the meso-position of BODIPY core was explored using a number of meso-unsubstituted BODIPY platforms. Spectral properties of the resulting meso-nitromethyl containing BODIPYs was found to be sensitive to the pH change as well as to the presence of water in organic solvents. Meso-nitromethyl group can be used for further modification of the BODIPY core via reduction or condensation reactions. DFT-PCM and TDDFT-PCM calculations correlate well with the experimental data and explain the observed spectral properties.

[Bis(trifluoroacetoxy)iodo]benzene (BTI) and (diacetoxyiodo)benzene (DIB) efficiently promote the formation of acylnitroso species from hydroxamic acids in the presence of various dienes to give the corresponding hetero-Diels–Alder (HDA) adducts in moderate to high yields. The present method could be applied to the HDA reactions of acylnitroso species with o-benzoquinones generated by the oxidative dearomatization of guaiacols.

Phenol based aryliodonium salts were prepared by the reaction of [hydroxy(tosyloxy)iodo]arenes with aryl silyl ethers in the presence of trifluoromethanesulfonic acid. Structures of several aryliodonium salts with the hydroxy group in the para-position of the phenyl ring were established by single crystal X-ray crystallography. Under basic conditions, 4-hydroxyphenyl(phenyl)iodonium salts form a dimeric hypervalent iodine(iii) complex, oxyphenyl(phenyl)iodonium ylidic salt, the solid structure of which was confirmed by X-ray crystallography. Phenolic iodonium salts are potentially useful phenol transfer reagents in reactions with various anionic nucleophiles.

A set of tetracyanobutadiene (TCBD)- and dicyanoquinodimethane (DCNQ)-bridged ferrocenyl dimers 5–8 were designed and synthesized by the [2 + 2] cycloaddition–retroelectrocyclization reaction of diferrocenyl complexes 3 and 4 with tetracyanoethylene (TCNE) and 7,7,8,8 tetracyanoquinodimethane (TCNQ), respectively. The effect of constitutional isomers (para vs meta) and different acceptors on their donor–acceptor interactions and photophysical and redox properties as well as electronic structures was evaluated using a variety of experimental and theoretical methods. The single-crystal X-ray structures of TCBD- and DCNQ-bridged ferrocenyl dimers 6 and 7 are reported. The DCNQ-bridged ferrocenyl dimers 7 and 8 have lower HOMO–LUMO gap values with red-shifted absorption bands in comparison to those of TCBD-bridged ferrocenyl dimers 5 and 6. Mossbauer spectra of 3–8 are suggestive of very similar isomer shifts and quadrupole splittings in all diferrocene complexes despite their different proximities to the ele...

Aiming at the enhancement of electrophilicity of imino-λ3-iodanes, we have developed (tosylimino)pentafluorophenyl-λ3-iodane, which shows superior reactivity compared to the commonly used (tosylimino)phenyl-λ3-iodane in the [2+2+1]-type synthesis of imidazoles.

Neutral and deprotonated anionic Ni(II), Pd(II), Cu(II), and Cu(III) complexes of tetrakis(perfluorophenyl)-N-confused porphyrin (PF-NCP) were prepared and investigated by UV-visible and magnetic circular dichroism (MCD) spectroscopies. As in the previously reported Ni(II) adduct of tetraphenyl N-confused porphyrin, we observe sign reverse (positive to negative intensities with increasing energy) features in the MCD spectra of the neutral Ni(II), Pd(II), and Cu(II) complexes of PF-NCP, which is indicative of rare ΔHOMOΔLUMO relationships. Upon deprotonation of Ni(II), Pd(II), and Cu(II) complexes, these features revert to those of more typical porphyrin MCD spectra consistent with a ΔHOMOΔLUMO condition. The Cu(III) PF-NCP complex shows features similar to those of the deprotonated divalent metal systems. Spectroscopic features in all target complexes as well as previously published metal-free and Ni(II) NCP systems were correlated with the density functional theory (DFT) and time-dependent DFT (TDDFT) calculations. Calculation data are consistent with the tautomeric rearrangement of the electronic structures of NCP cores playing dominant roles, with smaller contribution from the central metal ions in the observed optical and magneto-optical properties. This is true for all described NCP systems to date, as they affect the stabilization/destabilization of the N-confused porphyrin-centered Gouterman orbitals.

A metal-free meso-tetrakis([Formula: see text]-methoxycarbonylphenyl) N-confused porphyrin (1) was prepared as the precursor for water-soluble derivatives by the reaction between pyrrole, methyl-4-formylbenzoate, and MSA. Tautomeric behavior of the porphyrin 1 in polar and non-polar solvents was probed by [Formula: see text]H NMR, UV-vis, MCD, steady-state fluorescence, and high-resolution ESI methods and was found to be similar to the previously reported metal-free N-confused porphyrins. The electronic structure and the nature of the excited states in 1 were correlated with the results obtained by density functional theory (DFT) and time-dependent DFT (TDDFT) calculations.

NH-bridged and pyrazine-fused metallodiazaporphyrin dimers have been prepared from nickel(II) and copper(II) complexes of 3-amino-5,15-diazaporphyrin by Pd-catalyzed C-N cross-coupling and oxidative dimerization reactions, respectively. The synergistic effects of the nitrogen bridges and meso-nitrogen atoms play major roles in enhancing the light-harvesting properties and delocalization of an electron spin over the entire π-skeletons of the metallodiazaporphyrin dimers.

The 1,3,7,9-tetraferrocenylazadipyrromethene (3) and the corresponding 1,3,5,7-tetraferrocene aza-BODIPY (4) were prepared via three and four synthetic steps, respectively, starting from ferrocenecarbaldehyde using the chalcone-type synthetic methodology. The novel tetra-iron compounds have ferrocene groups directly attached to both the α- and the β-pyrrolic positions, and the shortest Fe-Fe distance determined by X-ray crystallography for 3 was found to be ∼6.98 Å. These new compounds were characterized by UV-vis, nuclear magnetic resonance, and high-resolution electrospray ionization mass spectrometry methods, while metal-metal couplings in these systems were probed by electro- and spectroelectrochemistry, chemical oxidations, and Mössbauer spectroscopy. Electrochemical data are suggestive of the well-separated stepwise oxidations of all four ferrocene groups in 3 and 4, while spectroelectrochemical and chemical oxidation experiments allowed for characterization of the mixed-valence forms in the target compounds. Intervalence charge-transfer band analyses indicate that the mixed-valence [3]

Several complexes of “PtL2” composition containing two cyanoxime anions – 2-oximino-2-cyano-N-piperidineacetamide (PiPCO−) and 2-oximino-2-cyano-N-morpholylacetamide (MCO−) – have been obtained and characterized both in solution and in the solid state. Complexes exist as two distinct polymorphs: monomeric yellow complexes and dark-green [PtL2]n 1D polymers, while for the MCO− anion a red, solvent containing dimeric [Pt(MCO)2·DMSO]2 complex has also been isolated. The interconversion of polymorphs was investigated. The monomeric PtL2 units are arranged into anisotropic extended solid [PtL2]n polymers with the help of Pt⋯Pt metallophilic interactions. Crystal structures of monomeric PtL2 (L = PiPCO−, MCO−) and red dimeric [Pt(MCO)2·DMSO]2 complexes were determined and revealed the cis-arrangement of cyanoxime anions. The Pt–Pt distance in the “head-to-tail” red dimer was found to be 3.133 A. The structure of the polymeric [Pt(PiPCO)2]n compound was elucidated using the EXAFS method and evidenced the formation of Pt-wires with ∼3.15 A intermetallic separation. The EPR spectra of both 1D polymers at variable temperatures indicate the absence of Pt(III) species. Both pure dark-green [PtL2]n polymers showed a considerable room temperature electrical conductivity of 20–30 S cm−1, which evidences the formation of a mixed valence Pt(II)/Pt(IV) system. We discovered that these 1D polymeric [PtL2]n complexes show an intense NIR fluorescence beyond 1000 nm, while yellow monomeric PtL2 complexes are not emissive at all. The room temperature excitation spectra of 1D polymeric [PtL2]n complexes demonstrated their strong emission beyond 1000 nm regardless of the used excitation wavelength between 350 and 800 nm, which is typical of systems with delocalized charge carriers. For the first time the formation of mixed valence “metal wires” held together by metallophilic interactions is directly linked both with an intense fluorescence in the NIR region of the spectrum and with the electrical conductivity. The effect of the concentration of [PtL2]n complexes dispersed in the dielectric salt matrix on the photoluminescence wavelength and intensity was investigated. Both polymers show a quantum yield that is remarkably high for this region of the spectrum, reaching ∼2%. Variable temperature emission of polymeric [PtL2]n in the −190–+60 °C range was studied as well.

We have developed a new synthetic strategy for the preparation of a series of isoindolin-1-imines and isoindolin-1-ones from aromatic ketones and phthalonitrile. Self-condensation reactions of these isoindolin-1-imines led to the formation of a novel class of benzo-fused, highly electron-deficient core-extended azadipyrromethene chromophores ("MB-DIPY"). The influence of temperature, catalyst, and the template ions on the self-condensation reaction rate, yield, and stereoselectivity was examined in detail. New chromophores (sodium, zinc, and metal-free compounds) were characterized by NMR, UV-vis, fluorescence, high-resolution mass spectroscopies, and in many cases, X-ray crystallography. Their redox properties were probed by electrochemical and spectroelectrochemical approaches that revealed the remarkable electron-accepting nature of the new systems. Stepwise one- and two-electron reduction of the new MB-DIPYs and their zinc complexes was investigated by spectroscopic and spectroelectrochemical methods. Both one- and two-electron reduced forms of all zinc complexes studied have strong absorption in the near-infrared region up to ∼1200 nm. Unusual spectroscopic and electrochemical properties of these dyes were correlated with their electronic structures and excited-state natures predicted by density functional theory (DFT) and time-dependent DFT calculations. Despite some structural similarities with well-known aza-BODIPYs, the new MB-DIPYs differ remarkably from them in spectroscopic and redox properties.

Diiminoisoindoline (DII) is a crucial reagent for the synthesis of phthalocyanine as well as related macrocycles and chelates such as hemiporphyrazine and bis(iminopyridyl)isoindoline. In this report, we present the synthesis and characterization of four 1,3-diylideneisoindolines prepared via the reaction of several organic CH acids and DII. These orange or red compounds exhibit intense π → π* transitions in the UV–visible region. The redox properties and electronic structures of all new compounds were investigated using cyclic voltammetry and density functional theory (DFT). The observed electrochemistry and UV–visible transitions are in good agreement with the DFT and time-dependent DFT calculations, which indicate that the HOMO is largely centered at the O═C–C–C═O fragments, and the lowest unoccupied molecular orbital is more extended onto the isoindoline unit.

We have explored the synthetic routes for regioselective formation of 2-pyridone[ a]- and 2-pyridone[ b]-fused BODIPYs using 1,3,5,7-tetramethyl-2,6-dicarbethoxy-BODIPY as the universal starting platform. While heterocyclization of the 3-(dimethylaminovinyl)-BODIPY and 3,5-bis(dimethylaminovinyl)-BODIPY results in the formation of mono-2-pyridone- and bis-2-pyridone[ b]-fused BODIPYs, respectively, similar heterocyclization of the 1,3-bis(dimethylaminovinyl)-BODIPY leads to the regioselective formation of the 2-pyridone[ a]-fused BODIPY core, which is the first example of heterocycle[ a]-fused BODIPYs. The regioselective formation of the 2-pyridone[ a]-fused BODIPY was further confirmed by X-ray crystallography and explained on the basis of the DFT and TDDFT calculations that are suggestive of the energy-favorable out-of-plane rotation of the dimethylaminovinyl group located at first position, which accelerates the reaction with n-butylamine. Trends in the UV-vis and fluorescence spectra of the BODIPYs 1-17 were discussed on the basis of DFT and TDDFT calculations.

Half-hemiporphyrazine macrocycles, which can be called “semihemiporphyrazines”, were synthesized using the Re(CO)3 unit as a templating agent. The products of these template reactions are six-coordinate rhenium complexes, with a facial arrangement of carbonyls, a halide, and a bidentate semihemiporphyrazine chelate that tilts out of the plane of coordination. Three types of semihemiporphyrazines can be produced from these reactions, depending on the alternate heterocycle to the isoindoline unit; structures including pyridine, thiazole, and benzimidazole were formed. The electronic structures of these compounds were probed using spectroscopy as well as density functional theory methods.

Several new 1,1′-bis(sulfonyl)ferrocenes designed for the synthesis of sulfonamide linked biological conjugates have been prepared. 1,1′-Bis(sulfonylbromide)ferrocene can be produced from the corresponding sulfonylchloride via a bis(sulfonylhydrazide) intermediate. Bis(sulfonyl-N-hydroxybenzotriazole)ferrocene can also be synthesized from the sulfonyl chloride, and reaction of glycine methyl ester with the sulfonyl chloride affords a [3]ferrocenophane complex. All new compounds have been structurally characterized by X-ray crystallography.

New pseudocyclic benziodoxole tosylates were prepared by the treatment of 1-hydroxybenziodoxolones with p-toluenesulfonic acid or via ligand transfer reaction between PhI(OH)OTs (Koser's reagent) and substituted 2-iodobenzoic acids under mild condition. Single crystal X-ray crystallography of these compounds revealed a pseudocyclic structure with a short intramolecular interaction of 2.362(3) A between oxygen and iodine in the iodoxole ring. Pseudocyclic benziodoxole tosylates readily react with various organic substrates as electrophiles or oxidants to afford the corresponding iodonium salts or the products of oxidation. Furthermore, these compounds can be used as efficient recyclable hypervalent iodine reagents. The reduced form of a pseudocyclic benziodoxole tosylate, 2-iodobenzoic acid, can be efficiently recovered from the reaction mixture by a simple acid-base liquid-liquid biphasic procedure.

The first hybrid di- and trinuclear iron(II)–zirconium(IV) and iron(II)–hafnium(IV) macrobicyclic complexes with one or two apical 5,10,15,20-tetraphenylporphyrin fragments were obtained using transmetalation reaction between n-butylboron-triethylantimony-capped or bis(triethylantimony)-capped iron(II) clathrochelate precursors and dichlorozirconium(IV)- or dichlorohafnium(IV)-5,10,15,20-tetraphenylporphyrins under mild conditions. New di- and trinuclear porphyrinoclathrochelates of general formula FeNx3((Bn-Bu)(MTPP)) and FeNx3(MTPP)2 [M = Zr, Hf; TPP = 5,10,15,20-tetraporphyrinato(2-); Nx = nioximo(2-)] were characterized by one-dimensional (1H and 13C{1H}) and two-dimensional (COSY and HSQC) NMR, high-resolution electrospray ionization mass spectrometry, UV–visible, and magnetic circular dichroism spectra, single-crystal X-ray diffraction experiments, as well as elemental analyses. Redox properties of all complexes were probed using electrochemical and spectroelectrochemical approaches. Electrochemical...

Acetyl ferrocene and diacetyl ferrocene both readily react with an excess of hydrazine to afford the corresponding hydrazone compounds. These compounds can then be linked to Re(CO)3 via a metal-mediated Schiff base reaction, resulting in a series of ferrocene-Re(CO)3 conjugates with different stoichiometries. Conjugates with 1:1, 1:2, and 2:1 ferrocene: Re(CO)3 ratios can be produced via this "modular" type synthesis approach. Several examples of these conjugates were structurally characterized, and their spectroscopic, electrochemical, and spectroelectrochemical behaviors were investigated. The electronic structures of these compounds were also probed using DFT and TDDFT calculations.

Mono- and di-(N-ferrocenyl-2-pyridone)-containing BODIPYs were prepared using a set of ferrocene-enamine cyclization reactions. The target compounds were characterized by UV-Vis, NMR, and mass spectrometry, while their redox properties were probed by the electrochemical, spectroelectrochemical, and chemical oxidation methods. Redox properties of the di-(ferrocenyl)-containing BODIPY are suggestive of a lack of electronic coupling between the two ferrocene groups. Oxidation of the ferrocene(s) in the target BODIPYs results in their observable fluorescence, while transient absorption spectroscopy data indicate fast electron-transfer from ferrocene donor to the photoexcited BODIPY acceptor. Density functional theory (DFT) and time-dependent DFT (TDDFT) methods were used to elucidate electronic structures of the organometallic BODIPYs and confirm the presence of the low-energy metal-to-ligand charge-transfer states in the NIR region.

A reaction between 5,10,15,20-tetra(4-hydroxyphenyl)porphyrin and 1-bromopyrene resulted in the formation of 5,10,15,20-tetra[4-(4-(pyrenyl-1)butoxy)phenyl]porphyrin (1), while cross-condensation between 4-(4-(pyrenyl-1)butoxy)benzaldehyde, ferrocenecaboxaldehyde, and pyrrole resulted in the formation of 5-ferrocenyl-10,15,20-tri[4-(4-(pyrenyl-1)butoxy)phenyl]porphyrin (2), 5,10-diferrocenyl-15,20-di[4-(4-(pyrenyl-1)butoxy)phenyl]porphyrin (3), and 5,15-diferrocenyl-10,20-di[4-(4-(pyrenyl-1)butoxy)phenyl]porphyrin (4). All pyrene-containing porphyrins were characterized by 1H NMR, UV-vis, MCD, and high-resolution ESI methods, while their electronic structures and the nature of the excited states were elucidated using density functional theory (DFT) and time-dependent DFT (TDDFT) calculations. The molecular structure of 1 and its fluorescence quenching upon the addition of C[Formula: see text] fullerene was also investigated using X-ray crystallography and steady-state fluorescence approaches.

A convenient procedure for oxidative cycloaddition of aldoximes with nitriles using stoichiometric or catalytic amounts of hypervalent iodine(III) reagent IBA-OTf (2-iodosylbenzoic acid triflate) has been developed. This efficient procedure works well for the preparation of various 1,2,4-oxadiazoles in generally high yields under mild reaction conditions. The actual oxidant in this reaction, IBA-OTf, is prepared from 2-iodosylbenzoic acid (IBA) and trifluoromethanesulfonic acid (TfOH) or it can be generated in situ from 2-iodobenzoic acid and m-chloroperoxybenzoic acid (m-CPBA) in the presence of TfOH. The nature of hydroxy(aryl)iodonium species, generated in situ from 2-iodobenzoic acid, m-CPBA, and TfOH under catalytic reaction conditions, has been confirmed by 1H NMR spectroscopy, ESI-mass spectrometry, and by X-ray diffraction.

New developments as well as a historic overview on synthetic strategies for preparation of the rare-earth complexes with porphyrins, phthalocyanines, naphthalocyanines, tetraazaporphyrins, and related systems are discussed in detail with emphasis on selective synthetic pathways for preparation of single-, double-, and triple-decker architectures.

Noncovalent π–π interactions between chloroboron subphthalocyanine (1), 2,3-subnaphthalocyanine (3), 1,4,8,11,15,18-(hexathiophenyl)subphthalocyanine (4), or 4-tert-butylphenoxyboron subphthalocyanine (2) with C60 and C70 fullerenes were studied by UV–vis and steady-state fluorescence spectroscopy, as well as mass (APCI, ESI, and CSI) spectrometry. Mass spectrometry experiments were suggestive of relatively weak interaction energies between compounds 1–4 and fullerenes. The formation of a new weak charge-transfer band in the NIR region was observed in solution only for subphthalocyanine 4 when titrated with C60 and C70 fullerenes. Molecular structures of the subphthalocyanines 2 and 4 as well as cocrystallite of 4 with C60 fullerene (4···C60) were studied using X-ray crystallography. One of the C60 fullerenes in the crystal structure of 4···C60 was found in the concave region between two subphthalocyanine cores, while the other three fullerenes are aligned above individual isoindole fragments of the aroma...

Two spherical organic–inorganic ferrocene-tin (hydr)oxide clusters of general formula [(FcSn)12O14(OH)6]X2 (Fc = ferrocenyl, X = nitroso-dicyanmethanide, DCO– and benzoylcyanoxime, PCO– anions) were prepared by the direct hydrolysis of Fc2SnCl2 or FcSnCl3 precursors in the presence of light- and thermally stable Ag(DCO) or Ag(PCO) salts. Molecular structures of FcSnCl3Py2 (1), Fc2SnCl2Py2 (2), [(FcSn)12O14(OH)6](DCO)2 (3), and [(FcSn)12O14(OH)6](PCO)2 (4) were investigated by X-ray crystallography. Density function theory (DFT) and time-dependent density functional theory (TDDFT) calculations were conducted on FcSnCl3Py2, Fc2SnCl2Py2, and [(FcSn)12O14(OH)6]2+ compounds in order to elaborate electronic structures and assign transitions in UV–vis spectra of these systems. The DFT and TDDFT calculations suggest that the organometallic substituents in the [(FcSn)12O14(OH)6]2+ core are rather isolated from each other.

A presence of bulky 2,6-di-iso-propylphenoxy groups in bis-tert-butylisocyano adduct of 2(3),9(10),16(17),23(24)-tetrachloro-3(2),10(9),17(16),24(23)-tetra(2,6-di-iso-propylphenoxy)-phthalocyaninato iron(II) complex allows separation of two individual positional isomers and a mixture of the remaining two isomers using conventional chromatography. X-ray structures of “[Formula: see text]” and “[Formula: see text]” isomers were confimed by X-ray crystallography. Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations of each individual positional isomer allowed insight into their electronic structures and vertical excitation energies, which were correlated with the experimental UV-vis and MCD spectra.

The bis(pyridylimino)isoindoline (BPI) ligand is a tridentate chelate that binds to metals via a meridional coordination mode. However, when this ligand forms a complex with Re(CO)(3), an almost exclusively facial moiety, the BPI ligand deforms to coordinate in a facial mode. We have in-vestigated this deformation via structural and theoretical means, and the non-planar binding mode of the ligand bathochromically shifts the metal to ligand charge transfer (MLCT) transition.