Trifluoroethoxy-Coating Improves the Axial Ligand Substitution of Subphthalocyanine

Applications of red light photoredox catalysis in organic synthesis

Photoredox catalysis has emerged as an efficient and versatile approach for developing novel synthetic methodologies. Particularly, red light photocatalysis has attracted more attention due to its intrinsic advantages of low energy, few health risks, few side reactions, and high penetration depth through various media. Impressive progress has been made in this field. In this review, we outline the applications of different photoredox catalysts in a wide range of red light-mediated reactions including direct red light photoredox catalysis, red light photoredox catalysis through upconversion, and dual red light photoredox catalysis. Due to the similarities between near-infrared (NIR) and red light, an overview of NIR-induced reactions is also presented. Lastly, current evidence showing the advantages of red light and NIR photoredox catalysis is also described.

Analysis of the Solvent Effects on the Crystal Growth of Peripherally Chlorinated Boron Subphthalocyanines

We report the characterization of the crystal/nano-structures for hexachloro-boron subphthalocyanines (Cl6BsubPc) grown via a variety of solvent diffusion methods and also with having axial substitutions variants: chloride; phenoxy; naphthoxy and...

Fluorinated boron subphthalocyanines: Lewis acid based templating chemistry facilitates random halide exchange, and fluoride versus chloride affects the basic photophysical properties and the solid-state arrangement

A sub-group of the phthalocyanine family, the boron subphthalocyanines (BsubPcs), have robust chemistry and can be readily modified at the axial and peripheral positions to tune their physical properties.

Increased Light-Harvesting in Dye-Sensitized Solar Cells through Förster Resonance Energy Transfer within Supramolecular Dyad Systems

Novel pyridine-substituted subphthalocyanines were prepared for an additional harvesting of a green spectral region of the solar light spectrum for zinc phthalocyanine-based dye-sensitized solar cells. These compounds can bind with the central metal of zinc phthalocyanines to form the corresponding supramolecular complexes as monitored by the absorption and fluorescence spectral changes. The stability constants of these complexes were altered by the number and position of pyridine units in the pyridine-substituted subphthalocyanines. On the basis of fluorescence titration study, the complexes efficiently transfer energy from the subphthalocyanine to zinc phthalocyanine. The solar cells using TiO₂ electrodes stained with the supramolecular complexes, composed of zinc phthalocyanine sensitizer and pyridine-substituted subphthalocyanines, showed panchromatic responses, and the photocurrent generation in the range of 500-600 nm is attributed to the efficient Förster resonance energy transfer from subphthalocyanine to zinc phthalocyanine on the TiO₂ surface.

Trifluoroethoxy-Coated Subphthalocyanines Attract Small Arenes in Their π-Concave Cavity

X-ray crystallographic analyses of a series of trifluoroethoxy-substituted subphthalocyanines disclosed that a molecule of toluene is clasped at the center of the molecular concave cavity. Twelve trifluoroethoxy substituents, which flexibly surround the toluene molecule to hold it on the 14 π-electron-conjugated surface of the subphthalocyanines, can also catch a molecule of benzene. In contrast, a nonsubstituted subphthalocyanine does not show the same phenomena, and two subphthalocyanine units are required to maintain a small aromatic compound in their concave cavity. DFT calculations of the complexes were conducted to better understand the arene clathrates. Trifluoroethoxy-substituted subphthalocyanines can be used to prepare arene clathrates as a result of their concave space. This is a unique approach to obtaining X-ray crystal structures of small noncrystalline aromatic compounds.

Subphthalocyanine basicity: reversible protonation at the azomethine bridge

Protonation of subphthalocyanine azomethine bridges is reversible and was evidenced by UV/Vis, ¹H-NMR and IR.

Synthesis and application of trifluoroethoxy-substituted phthalocyanines and subphthalocyanines

Phthalocyanines and subphthalocyanines are attracting attention as functional dyes that are applicable to organic solar cells, photodynamic therapy, organic electronic devices, and other applications. However, phthalocyanines are generally difficult to handle due to their strong ability to aggregate, so this property must be controlled for further applications of phthalocyanines. On the other hand, trifluoroethoxy-substituted phthalocyanines are known to suppress aggregation due to repulsion of the trifluoroethoxy group. Furthermore, the electronic characteristics of phthalocyanines are significantly changed by the strong electronegativity of fluorine. Therefore, it is expected that trifluoroethoxy-substituted phthalocyanines can be applied to new industrial fields. This review summarizes the synthesis and application of trifluoroethoxy-substituted phthalocyanine and subphthalocyanine derivatives.

Switching of Resistive Memory Behavior from Binary to Ternary Logic via Alteration of Substituent Positioning on the Subphthalocyanine Core

Two new axially or peripherally functionalized subphthalocyanines with the decoration of donor-acceptor substituents have been successfully synthesized, characterized and employed in the application of resistive memory device via solution-processable technique. Axially substituted subphthalocyanine shows ternary resistive memory behavior with well-separated current ratios of 1:10⁶:10⁸ between "OFF", "ON1" and "ON2" states, while only binary logic is observed for peripherally substituted subphthalocyanine. Computational studies show the presence of two well-separated charge transfer states in the axially substituted subphthalocyanine, while the charge transfer processes between the peripheral substituents and the subphthalocyanine core are found to be very close in energy. This work has demonstrated the impact of the substituent positioning on the subphthalocyanine-based memory device performance, providing a new research dimension for the future design and development of multistate organic resistive memory.

Trifluoroethoxy-Coated Subphthalocyanine affects Trifluoromethylation of Alkenes and Alkynes even under Low-Energy Red-Light Irradiation

Photoredox chemical reactions induced by visible light have undergone a renaissance in recent years. Polypyridyl dyes such as Ir(ppy)3 and Ru(bpy)3 are key catalysts in this event, and blue- or white-light irradiation is required for the chemical transformations. However, it remains a challenge to achieve reactions under the lower energy of red light. We disclose, herein, that trifluoroethoxy-coated subphthalocyanine realizes the red-light-driven trifluoromethylation of alkenes and alkynes with trifluoromethyl iodide in good-to-high yields. Perfluoroalkylations were also achieved under red light. The reaction mechanism is discussed with the support of UV/Vis spectroscopy and cyclic voltammetry of trifluoroethoxy-coated subphthalocyanine. Light irradiation/dark study also supports the proposed mechanism.

Axially diethylaminophenoxypropanoxy substituted new subphthalocyanines: synthesis and electropolymerization properties

The treatment of boron(III) subphthalocyanine chloride with 1,3-bis[3-(diethylamino)phenoxy]propan-2-ol 2 and 2,3-bis[3-(diethylamino)phenoxy]propan-1-ol 4 in toluene gave the corresponding axially substituted boron(III) subphthalocyanine compounds 3 and 5. The novel axially diethylaminophenoxypropanoxy substituted subphthalocyanines were characterized by standard spectroscopy methods. The electropolymerization properties of new axially diethylaminophenoxypropanoxy substituted subphthalocyanines were also characterized by using cyclic and square wave voltammetry techniques. This study is the first example of electropolymerization of axially substituted subphthalocyanines in the literature.

Design, synthesis and optical properties of unsymmetrical subphthalocyanine trimer connected by phloroglucinol via axial positions

Energy transfer from the non-substituted subphthalocyanine unit to the perfluorinated subphthalocyanine unit via a trifluoroethoxy substituted unit is suggested.

Process for the synthesis of symmetric and unsymmetric oxygen bridged dimers of boron subphthalocyanines (μ-oxo-(BsubPc)2s)

A process for the gram scale synthesis of the oxygen bridged dimer of boron subphthalocyanine, μ-oxo-(BsubPc)2, has been developed. During the development it was found that a wide range of reaction pathways under diverse conditions lead to μ-oxo-(BsubPc)2 formation. However, obtaining μ-oxo-(BsubPc)2 as the main reaction product in appreciable yields and its subsequent isolation were extremely challenging. The best balance of purity, yield and conversion was achieved with a time controlled reaction of an equimolar reaction of HO-BsubPc with Br-BsubPc in the presence of K3PO4. The purification involved sequentially Soxhlet extraction, Kauffman column chromatography and train sublimation. We have repeated the process and yields ranged from 27 to 30% of pure, doubly-sublimed μ-oxo-(BsubPc)2. This process also enabled the synthesis of unsymmetric μ-oxo-(BsubPc)2s by reaction of HO-BsubPc with Br-F12BsubPc, Cl-Cl6BsubPc and Cl-Cl12BsubPc. After synthesis the solution-state properties of the unsymmetric μ-oxo-(BsubPc)2s were investigated, and compared to the symmetric μ-oxo-(BsubPc)2 and more broadly to other BsubPcs. The electronic properties of μ-oxo-(BsubPc)2 were found to differ from its unsymmetric counterparts, but were found to be similar to halo-BsubPcs. Furthermore, the photophysical properties of μ-oxo-(BsubPc)2, both symmetric and unsymmetric, differed greatly from all other known BsubPcs.

Synthesis and optical properties of subphthalocyanine homo- and heterodimers axially connected via a hydroquinone linker

The electron transfer process between subphthalocyanines differs depending on the o-, m-, and p-geometries of the hydroquinone linker.

A phthalocyanine-subphthalocyanine heterodinuclear dimer: comparison of spectroscopic properties with those of homodinuclear dimers of constituting units

A phthalocyanine-subphthalocyanine heterodinuclear dimer has been disclosed for the first time with its unique flat-bowl-shaped structure revealed by X-ray crystallography. Its spectroscopic properties were compared with those of homodinuclear dimers of constituting units, as well as those of constituting monomeric units.

Structurally-modified subphthalocyanines: molecular design towards realization of expected properties from the electronic structure and structural features of subphthalocyanine

This feature article summarizes recent contributions of the authors in the synthesis of structurally-modified subphthalocyanines, which covers (1) modification of the conjugated system, (2) core-modification, and (3) exterior-modification.

Subporphyrins with an axial B-C bond

Axial fabrications of subporphyrins have been conveniently accomplished by the reaction of B(methoxo)triphenylsubporphyrin with Grignard reagents such as aryl-, heteroaryl-, ferrocenyl-, β-styryl-, phenylethynyl-, and ethylmagnesium bromides. The axial groups thus introduced are not conjugated with the subporphyrin core. This situation leads to effective fluorescence quenching of subporphyrins when the axial group is strongly electron donating such as 4-dimethylaminophenyl and ferrocenyl groups.

Synthesis of subphthalocyanines as probes for the accessibility of silica nanochannels

The synthesis of a new subphthalocyanine is reported. Its structural and photophysical properties are ideal for probing the accessibility of arrays of silica nanochannels.