Synthesis, Spectroscopy, and Electrochemistry of Tetra-tert-butylated Tetraazaporphyrins, Phthalocyanines, Naphthalocyanines, and Anthracocyanines, together with Molecular Orbital Calculations

Hybrid ultrasound and photoacoustic contrast agent designs combining metal phthalocyanines and PBCA microbubbles

Photoacoustic (PA) imaging is an emerging diagnostic technology that combines the penetration depth of ultrasound (US) imaging and the contrast resolution of optical imaging. Although PA imaging can visualize several endogenous chromophores to obtain clinically-relevant information, multiple applications require the administration of external contrast agents. Metal phthalocyanines have strong PA properties and chemical stability, but their extreme hydrophobicity requires their encapsulation in delivery systems for biomedical applications. Hence, we developed hybrid US/PA contrast agents by encapsulating metal phthalocyanines in poly(butyl cyanoacrylate) microbubbles (PBCA MB), which display acoustic response and ability to efficiently load hydrophobic drugs. Six different metal chromophores were loaded in PBCA MB, showing greater encapsulation efficiency with higher chromophore hydrophobicity. Notably, while the US response of the MB was unaffected by the loading of the chromophores, the PA characteristics varied greatly. Among the different formulations, MB loaded with zinc and cobalt naphthalocyanines showed the strongest PA contrast, as a result of high encapsulation efficiencies and tunable optical properties. The strong US and PA contrast signals of the formulations were preserved in biological environment, as demonstrated by in vitro imaging in serum and whole blood, and ex vivo imaging in deceased mice. Taken together, these findings highlight the advantages of combining highly hydrophobic PA contrast agents and polymeric MB for the development of contrast agents for hybrid US/PA imaging, where different types of information (structural, functional, or potentially molecular) can be acquired by combining both imaging modalities.

CO2 electro-reduction reaction via a two-dimensional TM@TAP single-atom catalyst

In this study, the possibility of using TM atom anchored monolayer TAP as a class of electrocatalysts (TM@TAP, TM = 3d and 4d transition metal) toward carbon dioxide reduction reaction (CO2RR) was systematically investigated using first-principles calculations. During screening potential catalysts, the possibility that H and OH block the active site was considered. Then, the reaction mechanisms of screened catalysts were explored in detail. Interestingly, the different catalysts demonstrated different selectivities. Our results demonstrate that Cr@TAP, Zn@TAP, Mo@TAP, and Cd@TAP are selective toward the HCOOH product with a limiting potential in the range of -0.33 to -0.71 V. Mn@TAP and Rh@TAP promote CO production. The reduction products of Fe@TAP and Co@TAP were CH3OH and HCHO, respectively. Tc@TAP and Ru@TAP can catalyze CO2 to yield the deep reduction product, i.e. CH4. Among these catalysts, Cr@TAP and Rh@TAP are highly active due to their lower limiting potentials of -0.33 V and -0.28 V, respectively, and Fe@TAP can promote the production of the desired CH3OH with a limiting potential of -0.51 V, which allow them to be promising electrocatalysts for the CO2RR. We hope that our study will provide some insights into the rational design of electrocatalysts and useful guidance for experimental researchers.

Anti-Kasha emissions of single molecules in a plasmonic nanocavity

Kasha's rule generally holds true for solid-state molecular systems, where the rates of internal conversion and vibrational relaxation are sufficiently higher than the luminescence rate. In contrast, in systems where plasmons and matter interact strongly, the luminescence rate is significantly enhanced, leading to the emergence of luminescence that does not obey Kasha's rule. In this work, we investigate the anti-Kasha emissions of single molecules, free-base and magnesium naphthalocyanine (H2Nc and MgNc), in a plasmonic nanocavity formed between the tip of a scanning tunneling microscope (STM) and metal substrate. A narrow-line tunable laser was employed to precisely reveal the excited-state levels of a single molecule located under the tip and to selectively excite it into a specific excited state, followed by obtaining STM-photoluminescence (STM-PL) spectrum to reveal energy relaxation from the state. The excitation to higher-lying states of H2Nc caused various changes in the emission spectrum, such as broadening and the appearance of new peaks, implying the breakdown of Kasha's rule. These observations indicate emissions from the vibrationally excited states in the first singlet excited state ( S1) and second singlet excited state ( S2), as well as internal conversion from S2 to S1. Moreover, we obtained direct evidence of electronic and vibronic transitions from the vibrationally excited states, from the STM-PL measurements of MgNc. The results obtained herein shed light on the energy dynamics of molecular systems under a plasmonic field and highlight the possibility of obtaining various energy-converting functions using anti-Kasha processes.

Macrocycle-Functionalized RGO for Gas Sensors for BTX Detection Using a Double Transduction Mode

To fabricate mass and resistive sensors based on reduced graphene oxide (RGO), we investigated the functionalization of RGO by tetra tert-butyl phthalocyanine (PcH2tBu), which possesses a macroring and tert-butyl peripheral groups. Herein, we present the gas sensor responses of the functionalized RGO toward benzene, toluene, and xylene (BTX) vapors. The RGO was obtained by the reduction of graphene oxide (GO) using citrate as a reducing agent, while the functionalization was achieved non-covalently by simply using ultrasonic and heating treatment. The sensor devices based on both QCM (quartz crystal microbalance) and resistive transducers were used simultaneously to understand the reactivity. Both the GO and the RGO showed less sensitivity to BTX vapors, while the RGO/PcH2tBu presented enhanced sensor responses. These results show that the p-network plays a very important role in targeting BTX vapors. The resistive response analysis allowed us to state that the RGO is a p-type semiconductor and that the interaction is governed by charge transfer, while the QCM response profiles allowed use to determine the differences between the BTX vapors. Among BTX, benzene shows the weakest sensitivity and a reactivity in the higher concentration range (>600 ppm). The toluene and xylene showed linear responses in the range of 100–600 ppm.

Photophysicochemical, sonochemical, and biological properties of novel hexadeca-substituted phthalocyanines bearing fluorinated groups

This study presents the preparation of a novel tetra-substituted phthalonitrile (1), namely, 3,6-bis(hexyloxy)-4,5-bis(4-(trifluoromethoxy)phenoxy)phthalonitrile (1) and its metal-free (2)/metal {M = Zn (3), Cu (4), Co (5), Lu(CH₃COO) (6), Lu (7)} phthalocyanines. A series of various spectroscopic methods (UV-vis, FT-IR, mass, and ¹H NMR spectroscopy) were performed for the characterization of the newly synthesized compounds. The potential of compounds 2, 3, and 6 as photosensitizing materials for photodynamic and sonophotodynamic therapies was evaluated by photophysical, photochemical, and sonochemical methods. The highest singlet quantum yields were obtained for the zinc phthalocyanine derivative 3 by performing photochemical and sonochemical methods. In addition, several biological activities of the new compounds 1-7 were investigated. The newly synthesized phthalocyanines exhibited excellent DPPH scavenging activity and also DNA nuclease activity. The antimicrobial activity of the new compounds was evaluated by the disc diffusion assay. Effective microbial cell viability inhibition was observed with phthalocyanine macromolecules. The photodynamic antimicrobial therapy of the phthalocyanines showed 100% bacterial inhibition when compared to the control. They also exhibited significant biofilm inhibition activity against S. aureus and P. aeruginosa. These results indicate that new phthalocyanines are promising photodynamic antimicrobial therapies for the treatment of infectious diseases.

Recent advances in electrocatalysis with phthalocyanines

Applications of phthalocyanines (Pcs) in electrocatalysis-including the oxygen reduction reaction (ORR), the carbon dioxide reduction reaction (CO₂RR), the oxygen evolution reaction (OER), and the hydrogen evolution reaction (HER)-have attracted considerable attention recently. Pcs and their derivatives are more attractive than many other macrocycles as electrocatalysts since, although they are structurally related to natural porphyrin complexes, they offer the advantages of low cost, facile synthesis and good chemical stability. Moreover, their high tailorability and structural diversity mean Pcs have great potential for application in electrochemical devices. Here we review the structure and composition of Pcs, methods of synthesis of Pcs and their analogues, as well as applications of Pc-based heterogeneous electrocatalysts. Optimization strategies for Pc-based materials for electrocatalysis of ORR, CO₂RR, OER and HER are proposed, based on the mechanisms of the different electrochemical reactions. We also discuss the structure/composition-catalytic activity relationships for different Pc materials and Pc-based electrocatalysts in order to identify future practical applications. Finally, future opportunities and challenges in the use of molecular Pcs and Pc derivatives as electrocatalysts are discussed.

Electronic structures of zinc octaalkylthio- and octaphenylthio-tetrapyrazinoporphyrazines, and comparison with those of phthalocyanines and pyrazinoporphyrazines

Eight strongly electron-donating alkylthio- or arylthio-groups have been introduced to a strongly electron-withdrawing pyrazinoporphyrazine (PyZ) core, to form the Zn complexes of octadecylthiolated ZnPyZ, (SDc)[Formula: see text]ZnPyZ, and octaphenylthiolated ZnPyZ, (S[Formula: see text])[Formula: see text]ZnPyZ, and their electronic structures studied by 1H NMR and electronic absorption spectroscopy. The strength of the ring current, aromaticity, and flow of charge were discussed by calculating the ring current, nucleus-independent chemical shift (NICS), and anisotropy of the current-induced density (ACID), respectively. Good agreement was seen for the results of these three calculations, demonstrating that a strong ring current of the macrocycle is produced when the aromatic ring fused to the tetraazaporphyrin core has a weaker diamagnetic ring current, [Formula: see text]. weaker aromaticity (negatively smaller NICS values). TD-DFT molecular orbital (MO) calculations succeeded in explaining the differences of the absorption spectra between these octathiolated ZnPyZs and those without thiolated groups. The singlet oxygen quantum yield in pyridine (0.62) of (S[Formula: see text])[Formula: see text]ZnPyZ was similar to that (0.61) of normal ZnPc.

Phenanthroline-Fused Phthalocyanine Analogues Having a Monovalent Corrole Inner Perimeter and 4nπ Nonaromatic Properties

Condensation of 4,5-bis(4-tert-butyl-2,6-dimethylphenoxy)phthalonitrile with 2,9-diamino-1,10-phenanthroline in the presence of M(OAc)₂ (M = Ni, Pd, Zn) afforded a series of phenanthroline-fused phthalocyanine analogues with a 16 π-electron skeleton. While the arrangement of elements along the inner perimeter of these macrocycles is the same as that of the hitherto reported trivalent corroles, they represent the first example of porphyrinoids possessing a monovalent corrole inner perimeter and nonaromatic characteristics as revealed by their spectroscopic data and theoretical studies.

Photoactive layers for photovoltaics based on near-infrared absorbing aryl-substituted naphthalocyanine complexes: preparation and investigation of properties

Photoactive layers based on substituted naphthalocyanines and conductive polymer MEH-PPV were prepared using the spin-coating technique and their conductivity was tested in dark and under illumination.

Novel method for preparing stable near-infrared absorbers: a new phthalocyanine family based on rhenium(i) complexes

Rational design of near-infrared (NIR) absorbing molecules is crucial for developing photofunctional materials. Here, we synthesized dinuclear and mononuclear Re(i) tricarbonyl phthalocyanine complexes that exhibit a sharp intense Q band in the NIR region. The unsymmetric coordination of electron-deficient metal unit(s) concomitantly produced a remarkable red shift of the Q band and improved the tolerance of the phthalocyanine ring to oxidation. This study presents a simple and effective strategy for the construction of NIR absorbers with high stability.

Synthesis and electronic properties of meso-tetra(3,4,5-trimethoxy)phenyl-porphyrin and -tetrabenzoporphyrin and their phosphorus complexes

meso-Tetra(3,4,5-trimethoxy)phenyl-porphyrin and -tetrabenzoporphyrin and their phosphorus complexes were synthesized and their electronic absorption and magnetic circular dichroism (MCD) spectra discussed based on TD-DFT molecular orbital (MO) calculations. Nucleus-independent chemical shift (NICS) and anisotropy of the induced current density (ACID) calculations were also carried out for metal-free (and phosphorus) tetrabenzoporphyrins in order to discuss the aromaticity and flow of electrons in the molecule.

Novel 2-naphthyl substituted zinc naphthalocyanine: synthesis, optical, electrochemical and spectroelectrochemical properties

New zinc naphthalocyanine with bulky 2-naphthyl groups was obtained. Aggregation drastically influences its optical and electrochemical behavior. Spectroelectrochemistry helps to establish the oxidation potential and reveals unusual color change.

One-step synthesis of ball-shaped metal complexes with a main absorption band in the near-IR region

The design of near-IR materials is highly relevant to energy and pharmaceutical sciences due to the high proportion of near-IR irradiation in the solar spectrum and the high penetration of near-IR light in biological samples. Here, we show the one-step synthesis of hexacoordinated ruthenium and iron complexes that exhibit a main absorption band in the near-IR region. For that purpose, novel tridentate ligands were prepared by condensation of two diimines and four cyanoaryl derivatives in the presence of ruthenium and iron template ions. This method was applied to a wide variety of cyanoaryl, diimine, and metal ion combinations. The relationship between the structure and the optical and electrochemical properties in the resulting complexes was examined, and the results demonstrated that these compounds represent novel near-IR materials whose physical properties can be controlled based on rational design guidelines. The intense absorption bands in the 700–900 nm region were assigned to metal-to-ligand charge transfer (MLCT) transitions, which should allow applications in materials with triplet excited states under irradiation with near-IR light.

Template-controlled on-surface synthesis of a lanthanide supernaphthalocyanine and its open-chain polycyanine counterpart

Phthalocyanines possess unique optical and electronic properties and thus are widely used in (opto)electronic devices, coatings, photodynamic therapy, etc. Extension of their π-electron systems could produce molecular materials with red-shifted absorption for a broader range of applications. However, access to expanded phthalocyanine analogues with more than four isoindoline units is challenging due to the limited synthetic possibilities. Here, we report the controlled on-surface synthesis of a gadolinium-supernaphthalocyanine macrocycle and its open-chain counterpart poly(benzodiiminoisoindoline) on a silver surface from a naphthalene dicarbonitrile precursor. Their formation is controlled by the on-surface high-dilution principle and steered by different metal templates, i.e., gadolinium atoms and the bare silver surface, which also act as oligomerization catalysts. By using scanning tunneling microscopy, photoemission spectroscopy, and density functional theory calculations, the chemical structures along with the mechanical and electronic properties of these phthalocyanine analogues with extended π-conjugation are investigated in detail.

Extending the π‐conjugation of phthalocyanine dyes, while synthetically challenging, has the potential to produce desirable new molecular materials. Here, the authors use a templated on‐surface approach to synthesize several extended phthalocyanine derivatives from the same building block, including a lanthanide superphthalocyanine and an open‐chain polycyanine.

Binary small molecule organic nanoparticles exhibit both direct and diffusion-limited ultrafast charge transfer with NIR excitation

Here we describe a facile, one-step synthesis of a binary organic nanoparticle composed completely of NIR-absorbing small molecules, a quatterylene diimide and a vanadyl napthalocyanine, using Flash Nanoprecipitation. We show that the molecules are co-encapsulated within an amphiphilic block copolymer shell by observing distinct ultrafast dynamics in the binary nanoparticles compared to nanoparticles of their individual components, which we rationalize as a photoinduced charge transfer. We then draw similarities between the charge transfer dynamics studied in our system and the charge dissociation process in macroscale organic bulk heterojunction blends for OPV applications by assigning the ultrafast time component (∼10 ps) to direct interfacial charge transfer and the slow component (70-200 ps) to diffusion limited charge transfer. This discovery can inspire the development of mixed-composition nanoparticles with new functionality for optoelectronic and theranostic applications.

Recent advances in chemistry of phthalocyanines bearing electron-withdrawing halogen, nitro and N-substituted imide functional groups and prospects for their practical application

Herein, we present an overview of the approaches for the synthesis of phthalocyanines bearing electron-withdrawing halogen-, nitro- and N-substituted imide functional groups in different positions of the phthalocyanine macrocycle.

Novel phenyl-substituted pyrazinoporphyrazine complexes of rare-earth elements: optimized synthetic protocols and physicochemical properties

Novel synthetic protocols based on both template and direct methods were developed for phenyl-substituted pyrazinoporphyrazine complexes of rare-earth elements.

Crown-substituted naphthalocyanines: synthesis and supramolecular control over aggregation and photophysical properties

Tetra-15-crown-5-naphthalocyanines as first representatives of crown-substituted π-extended phthalocyanines were synthesized and characterized. The possibility to control their aggregation and photophysical properties by reversible formation of supramolecular assemblies in the presence of KOAc was demonstrated.

[Design and Synthesis of Functional π Molecules and Their Application to Near-IR Materials]

　The combination of several aromatic rings and/or heterocycles can induce novel functions. This phenomenon is observed in porphyrin derivatives, commonly found in hemoglobin, in the active sites of P-450, etc. The ability of these structures to interact strongly with visible light accounts for today's increased interest in the development of rationally designed porphyrinoid-based optical materials. In the pharmaceutical sciences, designing near-IR materials can be a challenge due to the high transparency of near-IR light in biological samples. Phthalocyanines (Pcs) are robust organic dyes that are absorbed in visible light. A theoretical investigation of molecular orbitals of Pcs has revealed that the introduction of a phosphorus(V) atom into a macrocyclic core leads to a narrower highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gap. Following these studies, we found that certain types of Pc phosphorus(V) complexes display main absorptions beyond 1000 nm. Additionally, phosphorus(V) complexes with other azaporphyrinoids have been designed and synthesized via a relatively simple procedure. These complexes showed novel optical properties which are potentially useful in the pharmaceutical and material sciences. Furthermore, we have overcome the problem of organic radicals and antiaromatic compounds, which are generally considered to be unstable, by using a combination of serendipitous synthetic methodologies and spectroscopic techniques. These novel azaporphyrin compounds are robust and free from transition metals. They are relatively easy to synthesize and also exhibit predictable properties.

Singlet oxygen quantum yields and photostability of planar binuclear phthalocyanines

The singlet oxygen ([Formula: see text]O[Formula: see text] quantum yield of the near-infrared absorbing ([Formula: see text] [Formula: see text] 839 nm) planar [Formula: see text]-conjugated binuclear zinc phthalocyanine (ZnPc) was measured and compared to the [Formula: see text]O[Formula: see text] quantum yields of the mononuclear and the planar binuclear phthalocyanine without [Formula: see text]-conjugation between Pc rings. In addition, the photooxidative stability of the [Formula: see text]-conjugated binuclear Pc was determined and compared to the stabilities of the mononuclear ZnPc and the known near-infrared photosensitizer, zinc tetra-tert-butylnaphthalocyanine ([Formula: see text] 761 nm). The results are explained by DFT calculations and cyclic voltammetry.

Amphoteric phosphorous(V)-phthalocyanines as proton-driven switchable fluorescers toward deep-tissue bio-imaging

Spectral (optical absorption and emission) properties of three amphoteric phosphorous(V)-phthalocyanine derivatives, [P(Pc)(O)OH], where Pc=tetra(tert-butyl)phthalocyaninate (tbpc), tetrakis(2',6'-dimethylphenoxy)phthalocyaninate (tppc), and octakis(4'-tert-butylphenoxy)phthalocyaninate (obppc), have been investigated in ethanolic solutions. Spectral changes upon protonation/deprotonation (the reaction sites have been determined to be their axial ligands by magnetic circular dichroism study) are drastic and rapid. All the initial ([P(Pc)(O)OH]), protonated ([P(Pc)(OH)₂]⁺), and deprotonated ([P(Pc)(O)₂]^-) species are possessed with sufficient brightness (defined as the product of their molar extinction coefficient, ε (inM^-1cm^-1), and fluorescence quantum yield, Φ_F) in bio-imaging window (650-900nm). For example, spectral characteristics of the tbpc derivatives have been determined as follows: ε=1.65×10⁵ (absorption maximum 676nm) and Φ_F=0.80 (emission maximum 686nm) for [P(tbpc)(O)(OH)] while ε=1.45×10⁵ (697nm) and Φ_F=0.27 (714nm) for [P(tbpc)(OH)₂]⁺, and ε=2.25×10⁵ (662nm) and Φ_F=0.90 (667nm) for [P(tbpc)(O)₂]^-. Emission of tppc and obppc derivatives behave in essentially the same manner irrespective of nature of the peripheral substituents and hence Φ_F values are greater with increasing emission peak wavenumbers in line with the "energy gap law". These characteristics make these compounds promising candidates as chemical probes for deep-tissue bio-imaging.

Photocatalyst with annulated binuclear thioporphyrazine-enhancing photocatalytic performance by expansion of a π-electron system

A novel planar binuclear zinc hexa(2,3-bis(butylthio)) porphyrazine sharing one benzene ring was successfully synthesized, which exhibits superior photocatalytic activity compared to that of its mononuclear counterpart owing to the expansion of the π-electron system.

Topological Control of Columnar Stacking Made of Liquid-Crystalline Thiophene-Fused Metallonaphthalocyanines

The spontaneous organization of two-dimensional polyaromatic molecules into well-defined nanostructures through noncovalent interactions is important in the development of organic-based electronic and optoelectronic devices. Two regioisomers of thiophene-fused zinc naphthalocyanines ZnTNcendo and ZnTNcexo have been designed and synthesized to obtain photo- and electroactive liquid crystalline materials. Both compounds exhibited liquid crystalline behavior over a wide temperature range through intermolecular π-π interactions and local phase segregation between the aromatic cores and peripheral side chains. The structural differences between ZnTNcendo and ZnTNcexo affected the stacking mode in self-assembled columns, as well as symmetry of the two-dimensional rectangular columnar lattice. The columnar structure in liquid crystalline phase exhibited an ambipolar charge-transport behavior.

Four Dibutylamino Substituents Are Better Than Eight in Modulating the Electronic Structure and Third-Order Nonlinear-Optical Properties of Phthalocyanines

2(3),9(10),16(17),23(24)-Tetrakis(dibutylamino)phthalocyanine compounds M{Pc[N(C4H9)2]4} (1-5; M = 2H, Mg, Ni, Cu, Zn) were prepared and characterized by a range of spectroscopic methods in addition to elemental analysis. Electrochemical and electronic absorption spectroscopic studies revealed the more effective conjugation of the nitrogen lone pair of electrons in the dibutylamino side chains with the central phthalocyanine π system in M{Pc[N(C4H9)2]4} than in M{Pc[N(C4H9)2]8}, which, in turn, results in superior third-order nonlinear-optical (NLO) properties of H2{Pc[N(C4H9)2]4} (1) over H2{Pc[N(C4H9)2]8}, as revealed by the obviously larger effective imaginary third-order molecular hyperpolarizability (Im{χ((3))}) of 6.5 × 10(-11) esu for the former species than for the latter one with a value of 3.4 × 10(-11) esu. This is well rationalized on the basis of both structural and theoretical calculation results. The present result seems to represent the first effort toward directly connecting the peripheral functional substituents, electronic structures, and NLO functionality together for phthalocyanine molecular materials, which will be helpful for the development of functional phthalocyanine materials via molecular design and synthesis even through only tuning of the peripheral functional groups.

Preparation, optical and electrochemical properties, and molecular orbital calculations of tetraazaporphyrinato ruthenium (II) bis(4-methylpyridine) fused with one to four diphenylthiophene units

2,5-Diphenyl-3,4-dicyanothiophene (1) and phthalonitrile (2) were mixed and treated with ruthenium (III) trichloride, 4-methylpyridine, and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in 2-ethoxyethanol at 135°C, to produce low-symmetrical tetraazaporphyrins (TAPs) (3), (4), (5), and (6) with one to three thiophene rings. Two thiophene-annelated tetraazaporphyrins were isolated as opposite and adjacent isomers 4 and 5. The structure of 3 was determined by X-ray crystallography, showing that the thiophene ring linked at the 3,4-positions on the tetraazaporphyrin scaffold deviates from the mean plane of the four central pyrrole nitrogen atoms (N1-N3-N5-N7). Optical and electrochemical properties of the products were examined by UV-vis and magnetic circular dichroism (MCD) spectroscopy, together with cyclic voltammetry. In the (1)H NMR spectra, the signals of 4-methylpyridine coordinating to the central ruthenium atom appeared at a higher magnetic field than those of uncoordinated 4-methylpyridine itself due to the shielding effect of the TAP ring. Increasing the number of fused thiophene rings resulted in 1) lower magnetic field shifts of the signals of axially coordinated 4-methylpyridine in the (1)H NMR spectra, 2) lower energy shifts of the Q band absorption in the UV-vis spectra, and 3) decreasing (cathodic shift) of the first oxidation potentials. The structures of simplified model compounds were optimized using the DFT method with the Gaussian 09 program at the B3LYP/LANL2DZ level for the Ru atom and the B3LYP/6-31G (d, p) level for the C, H, N, and S atoms. The optimized structures were utilized to calculate the NMR shielding constants, the HOMO and LUMO orbital energies, and the electronic absorption spectra.

Cyclophanes containing bowl-shaped aromatic chromophores: three isomers of anti-[2.2](1,4)subphthalocyaninophane

The connection of bowl-shaped aromatic boron subphthalocyanines with anti-[2.2]paracyclophane resulted in the first observation of electronic communication between convex and concave surfaces. Three isomers of anti-[2.2](1,4)subphthalocyaninophane, described as concave-concave (CC), convex-concave (CV), and convex-convex (VV) according to the orientation of the subphthalocyanine units, were synthesized and characterized by various spectroscopic techniques, including (1) H NMR, electronic absorption, fluorescence, and magnetic circular dichroism spectroscopy and X-ray crystallography, together with molecular-orbital calculations. On going from the CC system to CV and further to VV, the Q band broadened and finally split as a result of through-space expansion of the conjugated systems, which were also reproduced theoretically.

Systematic investigation of phthalocyanines, naphthalocyanines, and their aza-analogues. Effect of the isosteric aza-replacement in the core

A series of zinc complexes of phthalocyanines, naphthalocyanines and their aza-analogs was studied and compared using UV-vis and MCD spectra, molecular calculations, and photophysical and electrochemical measurements.

Lipophilic M(α,α′-OC5H11)8phthalocyanines (M = H2 and Ni(ii)): synthesis, electronic structure, and their utility for highly efficient carbonyl reductions

This paper describes the electronic structure of (α,α′-n-OC₅H₁₁)₈-H₂Pc and (α,α′-n-OC₅H₁₁)₈-Ni(ii)Pc and highly efficient carbonyl reductions catalyzed by Ni(ii)Pc.