Unsymmetrical Phthalocyanines Research Articles

DSSCs based on unsymmetrical A3B type Zn(II) and TiO(IV) naphthalenephthalocyanine/porphyrin cocktail dyes: A potential alternative for ruthenium based sensitizers

To increase the efficiency of dye-sensitized solar cells (DSSCs), there is still a need for alternative dyes that can absorb a broad spectrum of sunlight and maintain high conversion efficiencies. In order to meet these requirements, a cocktail dye made up of novel phthalocyanines together with a porphyrin have been designed. The novel unsymmetrical phthalocyanines are two ferrocenylphenoxy-naphthalenephthalocyanine (FPNPc) with Zn (ZnFPNPc) or TiO (TiOFPNPc) at the inner core and 4-ferrocenylphenoxy and 4-carboxybenzo substituents at peripheral positions. In order to increase their UV–Vis absorption capacity, cocktails have been prepared with the synthesized new dyes (ZnFPNPc or TiOFPNPc) and YD2 porphyrin dye. The full characterization of novel synthesized dyes has been performed by UV–Vis absorption, FTIR, H1-NMR, MALDI-TOF, electrochemical, TD-DFT techniques. In this work we have prepared DSSCs based on YD2 and phthalocyanine dye molecule with different cocktail ratio (YD2 + ZnFPNPc or YD2 + TiOFPNPc ratios: 1:1, 1:2, 2:1, 1:3, 3:1, 1:4 and 4:1). The best solar cell performance has been performed in the cases of YD2 + ZnFPNPc (3:1) (9.96%) and YD2 + TiOFPNPc (3:1) (10.72%) cocktail dyes. Due to the high efficiency values obtained, these new cocktail dyes are expected to be a good alternative to the ruthenium-based complex dyes used in DSSCs and pave the way for potential alternative dyes.

Convenient syntheses of phthalocyanine and tetrabenzotriazaporphyrin (TBTAP) mono-alkynes; unhindered building blocks for click chemistry and beyond

Unsymmetrical phthalocyanines and related macrocycles are often desirable for covalent construction or the self-assembly of more complex architectures. Terminal alkynes are versatile in this regard because they are amenable to cross-coupling via Sonogashira-type reactions, alkyne-alkyne coupling via Glaser-type couplings, and triazole formation via Click reaction with azides. Here we describe two complementary syntheses to conveniently add a single alkyne onto the phthalocyanine peripheral position and onto the meso-phenyl group of an (aryl)tetrabenzotriazaporphyrin, here providing a remote link point that is insulated from the macrocycle.

A new highly Selective, sensitive and NIR spectrophotometric probe based on A2B2-Type of unsymmetrical phthalocyanine for hazardous Be2+ recognition

The aim of this work is to construct a new A2B2-type of unsymmetrical and ratiometric phthalocyanine (Pc) based-probe O-A2B2ZnPc to provide an effective solution to critical inadequacy to be experienced for the detection of hazardous Be2+. O-A2B2ZnPc enabling strong absorption and emission in Near-Infrared region (λabs-λem wavelengths of 694–712 nm) showed excellent selectivity and sensitivity toward Be2+ among competitive metal ions by both spectrophotometric and fluorometric methods. The probe with oligomeric Pc form in THF was degraded with the addition of aqueous Be2+ and arranged to J-aggregation form, resulting in a remarkably diminishing in Q-band at 694 nm as well as a new band formation at 746 nm, and a considerably decreasing in fluorescence emission. The probe has superior features for the determination of Be2+ such as high quantum efficiency and photochemical stability, rapid response (1 s), high selectivity and very low Limit of Detection (0.26 ppb and 1.5 ppb) for UV–Vis and fluorescence, respectively which are quite good values according to the permissible amount of Be2+ (4 ppb) in water as specified by World Health Organization. O-A2B2ZnPc can be shown among the best performing probes with its unique properties according to previous studies in the literature. In addition, the geometrical and spectral features of the O-A2B2ZnPc were analyzed in detail by DFT calculations.

A versatile study of novel A3B-type unsymmetric zinc(II) phthalocyanines containing thiazolidin-4-one: Their, carbonic anhydrase I, II isoenzymes, and xanthine oxidase inhibitors evaluation

In this study, four novel phthalocyanine complexes containing zinc metal were synthesized. After preparing the starting compounds (2-(4-hydroxyphenyl)-3-phenylthiazolidin-4-one 1 and 2-(4-(2-hydroxyethoxy)phenyl)-3-phenylthiazolidin-4-one 3 by the conventional method, they were reacted with 4-nitrophthalonitrile separately using K2CO3 in DMF. Compounds 2 and 4, are well-documented compounds for obtaining phthalocyanines. Subsequently, synthesized phthalonitrile compounds 2 and 4 were reacted with Zn(II) salt at high temperature in the presence of DBU to convert them into targeted symmetrical (2a, 4a) and unsymmetrical (2b, 4b) phthalocyanines under suitable conditions. Their photochemical, photophysical, and electrochemical features were then examined. These metallophthalocyanines indicated good solubility in some organic solvents, such as DMSO, DMF, THF, DCM, and CHCl3. Furthermore, the structures of ligands (1, 2, 3, 4) were determined by 1H NMR, 13C NMR, and FT-IR spectrometry, while complexes (2a, 2b, 4a, 4b) were determined by FT-IR, UV–Vis, fluorescence, and MALDI-TOF spectrometry. Inhibitory effects of ligand and phthalocyanine compounds (1, 2, 3, 4, 2a, 2b, 4a, 4b) against human erythrocyte carbonic anhydrase I (hCA I) and II (hCA II) isoenzymes, as well as cow's milk xanthine oxidase (XO), were examined. It was found that 2a, 2b, 4a, and 4b had strong inhibition effects at micromolar levels against all three. The compounds 2b and 4b showed stronger inhibition effects for hCA I and II than 2a and 4a. In the case of XO, although the inhibition effects of these molecules (2b, 4a, 4b) were similar, 2a had the strongest inhibition effect. Since CA and XO inhibitors are the target molecules of drug development studies to be used in the treatment of many diseases, the results of this study will aid drug design studies in the development of new XO and CA inhibitors.

Phenanthroline-fused unsymmetrical phthalocyanines chelating rhenium(I) tricarbonyl units: Synthesis, spectroscopy and electrochemical properties

Phenanthroline-fused unsymmetrical phthalocyanine (2-H) and its zinc complex (2-Zn) were treated with Re(CO)5Cl to give rhenium(I) tricarbonyl chloride chelates 1-H and 1-Zn respectively, which represent the first example of phthalocyanines with peripherally appended rhenium(I) complex units. The molecular structure of 1-Zn was determined by single crystal X-ray diffraction analysis. The electronic absorption, magnetic circular dichroism, and steady-state and time-resolved fluorescence spectra and the singlet oxygen (1O2) generation efficiencies of 1-H and 1-Zn were measured and compared with those of phenanthroline-fused unsymmetrical phthalocyanines 2-H and 2-Zn, and the corresponding symmetrical phthalocyanines 3-H and 3-Zn as well. The electrochemical properties of 1-H and 1-Zn were also studied by cyclic voltammetry and compared with those of 2-H and 2-Zn. The effects of unsymmetrical phenanthroline fusing and rhenium(I) chelating on the photophysical and electrochemical behaviors of phthalocyanines were highlighted based on the above investigations.

Phthalocyanine-Functionalized Magnetic Silica Nanoparticles as Anion Chemosensors.

Anionic species are one of the most common pollutants in residual and freshwaters. The presence of anthropogenic anions in water drastically increases the toxicity to living beings. Here, we report the preparation of a new optical active material based on tri(tosylamino)phthalocyanines grafted to ferromagnetic silica nanoparticles for anion detection and removal. The new unsymmetrical phthalocyanines (Pcs) proved to be excellent chemosensors for several anions (AcO−, Br−, Cl−, CN−, F−, H2PO4−, HSO4−, NO2−, NO3−, and OH−) in dimethyl sulfoxide (DMSO). Furthermore, the Pcs were grafted onto magnetic nanoparticles. The resulting novel hybrid material showed selectivity and sensitivity towards CN−, F−, and OH− anions in DMSO with limit of detection (LoD) of ≈4.0 µM. In water, the new hybrid chemosensor demonstrated selectivity and sensitivity for CN− and OH− anions with LoD of ≈0.2 µM. The new hybrids are easily recovered using a magnet, allowing recyclability and reusability, after acidic treatment, without losing the sensing proprieties.

Insight into the effects of the anchoring groups on the photovoltaic performance of unsymmetrical phthalocyanine based dye-sensitized solar cells.

Push-pull zinc phthalocyanine dyes bearing hexylsulfanyl moieties as electron donors and carboxyethynyl as mono- or di-anchoring groups have been designed, synthesized and tested as sensitizers in dye-sensitized solar cells (DSSCs). The effects of the anchoring groups on the optical, electrochemical and photovoltaic properties were investigated. The incorporation of a carboxyethynyl group in GT23 has a considerable effect on preventing dye aggregation due to its relatively non-planar structure. The mono-anchoring dye bearing a phenyl carboxyethynyl group, GT5, has a higher molar extinction coefficient and sufficient charge injection into the TiO2 conduction band. Therefore, GT5 achieved at least 90% higher power conversion efficiency than the di-anchoring dyes (GT31 and GT32). Time-dependent density functional theory (PBE0/6-31G(d,p)) was also used to calculate the electronic absorption spectra, which predicted very well the measured UV-Vis with an error of up to 0.11 eV for the Q bands and 0.3 eV for the B bands. The longest charge transfer bands are obtained in the visible light region and they correspond to a transfer phthalocyanine core → substituent with a carboxyethynyl group where the absorptions of GT32 (465 nm) and GT31 (461 nm) are red-shifted compared to GT23 (429 nm) and GT5 (441 nm). The interaction energy between the phthalocyanine and a cluster of anatase-TiO2 (H4Ti40O82) was calculated using density functional theory. For all phthalocyanines, the interaction favored is monodentate and corresponds to -O(OH)Ti(TiO2), where the stronger interaction occurs for GT32 (-2.11 eV) and GT31 (-2.25 eV). This study presents the molecular combination of the anchoring groups in zinc phthalocyanine sensitizers, which is one of the effective strategies for improving the performance of DSSCs.

A new perspective on the beryllium sensor platform: Low symmetry phthalocyanine-based molecular design and ultra trace amount Be2+ ion recognition in aqueous media

New multichannel sensors based on unsymmetrical phthalocyanines (P—A3BZnPc (1) and its water-soluble form Q—A3BZnPc (2)) were developed for Be2+ determination in water and THF. The structures of the sensors were elucidated by single-crystal X-ray diffraction and spectroscopic methods such as 1H- and 13C-NMR, IR, MALDI-TOF-MS, UV–vis, and steady-state fluorescence. The sensors (1) and (2) are dual-channel sensors and operate in the NIR region with λabs-λemm wavelengths of 685 nm –702 nm and 690 nm–706 nm, respectively. The selectivity of the sensors against Be2+ was explored in the presence of different metal ions (Li+, Na+, K+, Cs+, Mg2+, Ca2+, Ba2+, Al3+, Hg2+, Ni2+, Cd2+, Zn2+, Fe2+, Co2+, and Fe3+) and no significant interference was reported except Co2+, causing an interference only for sensor (2). Limit of Detection (LOD) measurements gave LOD values around 2.9 ppb, which is lower as compared to the threshold value in aqueous solution (4 ppb), determined by the World Health Organization (WHO). The response times of the sensors, estimated by UV–vis and fluorescence spectroscopy techniques, were found to be 0.7 s and 0.6 s, respectively. Owing to these short response times, the sensors can be included in the class of fast sensors when compared with other sensors given in the literature. The results prominently indicate that the sensors developed in this work are highly selective and sensitive to Be2+ and have a potential of usage in the detection of Be2+ in aqueous media.

The Synthesis, Characterization, Electrochemical and Spectroelectrochemical Properties of Novel Unsymmetrical Phthalocyanines Containing Naphthoic Acid and Di-tert-butylphenoxy Groups

In this study, novel A3B-type unsymmetrically tetrasubstituted metallo and metal free phthalocyanine compounds were synthesized by a statistical condensation method using two differently substituted precursors, 4-(6-carboxy-2-naphthoxy) phthalonitrile and 4-(2,4-di-tert-butylphenoxy) phthalonitrile. The structures of the synthesized phthalocyanine compounds (ZnPc, CuPc, CoPc, NiPc and H2Pc) were characterized with spectroscopic techniques of FT-IR, UV-Vis, 1H-NMR, MALDI-TOF MS and elemental analysis. Electrochemistry of metallophthalocyanines (MPcs) was studied and electrochemical responses were compared with each other in order to understand the influence of the cations in the Pc core and substituent environment to the redox responses of them. Electrochemical characterizations indicated that one metal based reduction and one metal based oxidization processes were observed with CoPc in addition to the Pc based electron transfer reactions. Moreover ZnPc, CuPc, NiPc, and H2Pc only indicated Pc ring based redox couples. Extraordinarily, all complexes were electrodeposited on the working electrode surface during the reduction reactions which intensively altered the redox behaviors of the complexes. In situ spectroelectrochemical characterizations supported the voltammetric assignments and indicated electrocheromic functionality of the complexes. ZnPc was tested as potential dye for DSSCs and illustrated reasonable photovoltaic performance.

Unsymmetrical phthalocyanines containing azo moiety; Synthesis and photophysical properties

Unsymmetrical metal-free phthalocyanine was synthesized through cyclotetramerization of 4-[2,6-dimethyl-4-(4-tert-butyl-phenylazo)phenoxy]phthalonitrile and 4-(hexylthio)phthalonitrile in the presence of lithium in [Formula: see text]-pentanol, then metal-free phthalocyanine was obtained by acidification with acetic acid. Finally, metalation was achieved by refluxing metal-free phthalocyanine in [Formula: see text]-pentanol in the presence of zinc (II) salt. The structure of synthesized phthalocyanine derivatives were characterized by using proton nuclear magnetic resonance, mass spectrometry, ultraviolet–visible spectroscopy, and Fourier transform infrared spectroscopy. The HOMO–LUMO energies were computed using density functional theory. The HOMO–LUMO energy difference is 2.28 eV. The calculated results were consistent with the experimental data. In addition, aggregation behaviors and general trends for photophysical properties of these phthalocyanine derivatives were studied in tetrahydrofuran. The emission intensities of these phthalocyanine derivatives were strongly quenched by 1,4-benzoquinone in tetrahydrofuran.

O-Carborane, Ferrocene, and Phthalocyanine Triad for High-Mobility Organic Field-Effect Transistors.

An unsymmetrical zinc phthalocyanine with ferrocenylcarborane linked to the phthalocyanine ring through a phenylethynyl spacer was designed for organic field-effect transistor (OFET). The unsymmetrical phthalocyanine derivatives were characterized using a wide range of spectroscopic and electrochemical methods. In particular, the ferrocenylcarborane structure was unambiguously revealed based on the single-crystal X-ray diffraction analysis. In-depth investigations of the electrochemical properties demonstrated that the ferrocenylcarborane insertion extended the electrochemical character of ferrocenylcarborane-substituted phthalocyanine (7). Moreover, in the anodic potential scans, the oxidative electropolymerization of etynylphthalocyanine (6) and 7 was recorded. To clarify the effect of the insertion of ferrocenylcarborane (2) on the field-effect mobility, solution-processed films of 2, 6, and 7 were used as an active layer to fabricate the bottom-gate top-contact OFET devices. An analysis of the output and transfer characteristics of the fabricated devices indicated that the phthalocyanine derivative functionalized with ferrocenylcarborane moiety has great potential in the production of high-mobility OFET.

Synthesis and photophysical and electrochemical properties of novel unsymmetrical phthalocyanines with a Sudan IV moiety

The synthesis of novel, A[Formula: see text]B type unsymmetrical metal-free and metallophthalocyanines bearing one aza dye group Sudan IV and three nitro terminal moieties was achieved by cyclotetramerization of novel 4-((1-((E)-(2-methyl-4-((E)-[Formula: see text]-tolyldiazenyl)phenyl)diazenyl)naphthalen-2-yl)oxy)phthalonitrile and 4-nitrophthalonitrile. The new unsymmetrical metal-free and metallophthalocyanines have been characterized using elemental analyses, [Formula: see text]H NMR, FT-IR, UV-vis and mass spectroscopic data. The aggregation properties of the compounds were investigated in a concentration range of 1.0 × 10[Formula: see text] M–6.25 × 10[Formula: see text] M. General trends were also studied for fluorescence quantum yields and lifetimes of these phthalocyanine compounds in tetrahydrofuran. The fluorescence of the synthesized unsymmetrical metal-free and metallophthalocyanines is effectively quenched by 1,4-benzoquinone (BQ) in THF. In-depth investigation of the electrochemical properties showed that nitro groups extended the reduction potentials.

A novel polystyrene with non-symmetrical zinc phthalocyanines as terminal group

A new non-symmetrical zinc(II) phthalocyanine (ZnPc) with an alkynyl functional group was prepared by an efficient mixed statistical condensation of 4-((4-ethynylbenzyl)oxy)phthalonitrile (1) and 4-(4-tert-butylphenoxy)phthalonitrile (2). The isolated unsymmetrical phthalocyanine molecule with additional three 4-tert-butylbenzyloxy groups to maintain solubility was used in the Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition, better known as the “click chemistry”, as one of the precursors. The second component of the click reaction was polystyrene (PS) which was obtained by atom transfer radical polymerization (ATRP) and then its bromo end group was converted to azide by treatment with sodium azide. FT-IR, 1H-NMR, 13C-NMR, MALDI TOF MS, UV–Vis, GPC, and elemental analysis techniques were used to characterize the precursors and targeted ZnPc-functionalized polystyrene. Molecular weight of obtained polymer was examined by gel permeation chromatography (GPC), thermal properties were also evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). It is observed that thermal stability of PS-ZnPc has been improved owing to high thermal stability of phthalocyanine group. Surface properties of PS-ZnPc thin films investigated by contact angle measurements indicate that it has more hydrophobic character when compared with PS-Br film.

Modifications of an unsymmetrical phthalocyanine: Towards stable blue dyes for dye-sensitized solar cells

A new copper phthalocyanine, namely 9(10),16(17),23(24)-tri-tert-butyl-2-[acetynyl-(4-carboxy)phenyl]phthalocyaninatocopper and its related free base have been synthesized as potential stable blue dyes for dye sensitized solar cells. The molecule structure consists on an unsymmetrically-substituted macrocycle bearing three tert-butyl groups and one phenylethynyl moiety as peripheral substituents and it is analogue to that of a previously published zinc derivative. Chemical and optical characterizations, as well as theoretical calculations of the frontier orbitals of both molecules are discussed. To evaluate the effect of the central metal on the photovoltaic behavior of this dye, the novel molecules have been both tested and confronted with the zinc derivative. This last one has shown efficiency values significantly higher than those previously published with a 2.10% maximum efficiency, while the other two dyes yielded 1.66% and 1.38% maximum efficiency respectively.

Synthesis of an ABCD-Type Phthalocyanine by Intramolecular Cyclization Reaction.

Unsymmetrical phthalocyanines with a low symmetry can exhibit unique and intriguing properties that can facilitate their applications in certain disciplines. The synthesis of these compounds, however, has posed a great difficulty. A novel and unprecedented approach for phthalocyanine synthesis is reported that involves intramolecular cyclization of prelinked tetrakisphthalonitriles. By using this strategy, the first ABCD-type phthalocyanine has been prepared in 7.2% yield.

A comparative physicochemical study of unsymmetrical indium phthalocyanines in the presence of magnetic nanoparticles or quantum dots

Asymmetric indium phthalocyanine (3, containing an NH2 group) was conjugated (via an amide bond) to magnetic nanoparticle (MNP) functionalized with carboxylic acid or glutathione-capped CdTe/ZnSe/ZnO quantum dots to form 3-MNPs or 3-QDs. Techniques such as time-resolved fluorescence measurements, transmission electron microscopy, XPS, elemental analysis, FTIR, NMR (1H, 13C, and cozy), electronic spectroscopy, as well as mass spectroscopy were employed to characterize 3 and its nanoconjugates. The phthalocyanine conjugated to quantum dot (3-QDs) possesses the lowest Фpd higher Ф∆ and ФT as well as longer triplet lifetimes compares to 3-MNPs and free phthalocyanine.

Unsymmetrical Phthalocyanines With One TTF unit and Octylthio or Octylsulfonyl Groups: Their Optical and Electrochemical Properties

Unsymmetrical Phthalocyanines With One TTF unit and Octylthio or Octylsulfonyl Groups: Their Optical and Electrochemical Properties

4-tert-butylphenoxy substituted phthalocyanine with RGD motif as highly selective one-photon and two-photon imaging probe for mitochondria and cancer cell

An unsymmetrical phthalocyanine based one- and two-photon fluorescence imaging probe that substituted with 4-tert-butylphenoxy and RDGyK moieties was developed and characterized by UV-vis and high-resolution MALDI-TOF/MS. The conjugate is non-aggregated in [Formula: see text],[Formula: see text]-dimethylformamide, with relatively weak fluorescence emission ([Formula: see text] 0.023) and high singlet oxygen quantum yield ([Formula: see text] 0.55). Conjugation of the cyclic peptide sequence c(RGDyK) can enhance the cellular uptake towards the DU145 and PC3 cells. While the fluorescence is greatly enhanced in mitochondria, the conjugate is non-cytotoxicity either in dark or upon exposure to red-light with dose up to 12 J.cm[Formula: see text]. The results suggest that this conjugate is a promising multifunctional imaging probe for mitochondria and cancer.

A new unsymmetrical phthalocyanine with a single o-carborane substituent

Unsymmetrical zinc phthalocyanine carrying a single o-carborane substituent on the peripheral position was synthesized in a multistep reaction sequence. At the first step, metal-free phthalocyanine 3 was prepared by cyclotetramerization of 4,5-di(hexylthio)phthalonitrile and 4-(2-hydroxyethylthio)phthalonitrile in pentanol in the presence of lithium; and zinc phthalocyanine 4 was prepared by insertion of Zn(II) salt. After esterification of phthalocyanine 4 with 4-pentynoic acid, terminal alkynyl bearing precursor phthalocyanine 5 was obtained. At the last step, reaction of decaborane with phthalocyanine 5 yielded phthalocyanine 6 with the desired o-carborane moiety. The new phthalocyanine compounds were characterized by elemental analysis, NMR, FT-IR, UV–vis and mass spectral data. Aggregation behaviour and electrochemical properties of these newly synthesized unsymmetrical phthalocyanine derivatives were also reported.

Unsymmetrical pyrene-fused phthalocyanine derivatives: synthesis, structure, and properties.

Novel pyrene-fused unsymmetrical phthalocyanine derivatives 2,3,9,10,16,17-hexakis(2,6-dimethylphenoxy)-22,25-diaza(2,7-di-tert-butylpyrene)[4,5]phthalocyaninato zinc complex Zn[Pc(Pz-pyrene)(OC8 H9 )6 ] (1) and 2,3,9,10-tra(2,6-dimethylphenoxy)-15,18,22,25-traza(2,7-di-tert-butylpyrene)[4,5]phthalocyaninato zinc compound Zn[Pc(Pz-pyrene)2 (OC8 H9 )4 ] (2) were isolated for the first time. These unsymmetrical pyrene-fused phthalocyanine derivatives have been characterized by a wide range of spectroscopic and electrochemical methods. In particular, the pyrene-fused phthalocyanine structure was unambiguously revealed on the basis of single crystal X-ray diffraction analysis of 1, representing the first structurally characterized phthalocyanine derivative fused with an aromatic moiety larger than benzene.