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Modification of nanomaterials through electrochemical grafting is a useful approach to introduce linking groups on to the surface of these structures. This work shows the possibility of applying electrochemical grafting to branched multiwalled carbon nanotube paper with an electrical resistance of 0.1 ohm-cm, and subsequent reaction of the grafted 4-azidobenzenediazonium with ethynylferrocene through the Sharpless click chemistry reaction. A comparison is made between this paper electrode and adsorbed single-walled carbon nanotubes on a glassy carbon electrode, with electrochemistry, X-ray photoelectron spectroscopy and scanning electrochemical microscopy used for characterization.

A new bis(aroylacetylene) containing triazole and fluorene moieties is synthesized by click chemistry. Polycyclotrimerization of the monomer is catalyzed by piperidine in refluxed dioxane, furnishing a regioregular poly(aroylarylene) in a satisfactory yield. The hyperbranched structure of the polymer is characterized spectroscopically with satisfactory results. The polymer enjoys no metal detriment and is soluble in common organic solvents such as tetrahydrofuran (THF), chloroform, dichloromethane (DCM), and N,N-dimethylformamide (DMF).

Liquid crystalline polymers containing 1,2,3-triazole units as linking groups have been synthesized from the monomers containing triad ester diazide and flexible dialkyne ester by 1,3-cycloaddition reaction and were characterized. Click reaction of azide and alkyne functionals catalyzed by Cu(I) yielded target polyesters with 1,2,3-triazole groups. The structure of the polymer was confirmed by spectral techniques. GPC analysis reveals that the polymers have moderate molecular weight with narrow distribution. Hot stage optical polarizing microscopic investigation confirms the liquid crystalline nature of the polymers with lengthy flexible spacers, while the short chain containing polymers does not show the mesomorphic properties. Differential scanning calorimetric analysis confirms the formation of mesophase in some of the polymers, and it is in accordance with the microscopic results. Thermal stabilities of the polymers were analyzed by thermogravimetric analysis.

The review summarizes the synthesis and study of properties of the bioconjugates of chlorophyll a and bacteriochlorophyll a with carbohydrates, carboranes and other moieties, focusing on the synthetic methods of obtaining conjugates and preliminary biological testing thereof. Boronated chlorins and bacteriochlorins can be used in both photodynamic and boron neutron capture therapy.

Using a Cu(I)-catalyzed carbohydrate azide-alkynylphenylporphyrin cycloaddition (the so-called "click" chemistry), we have synthesized in high yields, a series of four new porphyrin-carbohydrate conjugates containing either one or four galactose or lactose moieties linked via triazole units to a meso-phenyl group of a TPP or tetrabenzoporphyrin (TBP) macrocycle. The time-dependent uptake and subcellular distribution of this series of porphyrin-carbohydrate conjugates were evaluated in human carcinoma HEp2 cells. While the three TPP conjugates accumulated to a similar extent within cells and localized mainly in the ER and endosomes, the TBP-galactose conju gate was the one most efficiently taken up by the HEp2 cells, accumulating approximately 5 times more than the TPP conjugates, and localized preferentially within the cell lysosomes.

Glucose-, galactose- and lactose-containing photosensitizers based on derivatives of chlorophyll a and bacteriochlorophyll a were synthesized with the use of [3+2] cycloaddition between sugar azides and triple bond derivatives of chlorins and bacteriochlorins. Unlike bacteriochlorin cycloimide, chlorin was detected to form a Cu-complex during the click reaction. An approach to the synthesis of metal-free glycosylated chlorins was developed with the use of "protection" by Zn²⁺ cation and subsequent demetalation. It is based on the action of alkynyl chlorin e₆ derivative Zn-complex, which is resistant to the substitution by copper cation. Bacteriochlorin p cycloimide conjugate with per-acetylated β-D-lactose was obtained and shown to become water-soluble after unblocking of the lactose hydroxy functions. NMR studies allowed for the elucidation of structure, tautomeric form and conformation of the obtained compounds.

A series of new zinc phthalocyanine dendrimers with an increasing branched shell of oligoethylene glycol end groups has been synthesized. Owing to the presence of these hydrophilic termini at the dendrimer surface, all compounds are highly soluble in a wide range of solvents including water. The monodispersity of the amphiphilic dendrimers has been unambiguously evidenced by both NMR and MS techniques. UV-vis experiments point out that the tendency of the central phthalocyanine chromophore to aggregate in polar protic solvents is not significantly reduced regardless of the dendritic shell surrounding the macrocyclic chromophore.

The review aims at being an exhaustive summary of the use of Huisgen azide-alkyne dipolar addition in the synthesis of tetrapyrrolic compounds, mainly porphyrins, phthalocyanines, chlorins and bacteriochlorins.

A regioselective synthesis of glycoconjugates based on bacteriochlorophyll a and lactose derivatives has been carried out. The conjugation was achieved via 1,3-dipolar cycloaddition of bacteriochlorins containing a terminal triple bond and a lactose azide derivative. The conjugates obtained in this way had one or two disaccharide fragments attached to pyrrol A, the exocyclic imide ring of the tetrapyrrolyc macrocycle, or to both positions. Exhaustive NMR analysis by 1D and 2D NMR experiments (¹H-¹H COSY, TOCSY, ROESY, ¹H-¹³C HSQC, HMBC, and ¹H-¹⁵N HMBC) allowed us to determine the structures and configurations of the glycoconjugates obtained. A bioassay of the glycoconjugates using the Hep2 cell line showed that the highest efficiency was observed for the glycosylated bacteriopurpurinimide containing a lactose residue at pyrrole ring A.

The design and synthesis of new molecular hybrids composed of protoporphyrin IX (PPIX) and vitamin B₁₂ via copper catalyzed alkyne azide cycloaddition reaction is described. New, clickable aminoazide and aminoalkyne linkers were prepared and subsequently attached to PPIX (via vinyl group) and to vitamin B₁₂ giving desired building blocks. Preliminary results showed that respective water soluble hybrids were formed under CuAAC reaction. Gratifyingly, Cu incorporation into the PPIX core was avoided, which was important for further biological studies.

The synthesis of novel, symmetrical zinc(II) phthalocyanine (ZnPc) bearing four ethynylcyclohexyloxy terminal moieties was achieved by cyclotetramerization of novel 4-(2-ethynylcyclohexyloxy) phthalonitrile in pentanol in the presence of DBU and zinc acetate without any protective/deprotective chemistry. Subsequently, this new zinc(II) phthalocyanine derivative was reacted with 6-azido-hexanoic acid under "click-chemistry" conditions to give phthalocyanine-hexanoic acid conjugates linked by 1,2,3-triazole units. The new compounds have been characterized by using elemental analyses, UV-vis, FTIR, ¹H NMR and mass spectroscopic data. The aggregation properties of the compounds were investigated in different concentrations. General trends are also described for fluorescence quantum yields and lifetimes of novel zinc derivatives in tetrahydrofuran. The fluorescence of the tetrasubstituted zinc(II) phthalocyanine complexes is effectively quenched by 1,4-benzoquinone (BQ) in THF.

Click chemistry has been successfully applied to prepare a conjugate of zinc(II) porphyrin with four boron dipyrromethene moieties. Upon excitation at the latter, an efficient excitation energy transfer to the porphyrin core occurs with an energy transfer quantum yield of 0.98, making this conjugate a promising light-harvesting system.

Two isomers of porphyrin trimer with 1,4-diaryltriazole linkers have been synthesized using "click" methodology and characterized by MS, NMR and UV-vis spectroscopy. The porphyrin compounds were shown to exhibit photostability and high solubility. Photophysical data were compared with corresponding ones of synthesized triazole-bridged dimer with the same electronic surrounding and known linear dimer and trimer with diarylethyne linkers. Obtained data revealed weak inter-chromophore electronic communication in the ground state but significant exciton coupling whereas the properties of the individual chromophores are mainly retained for triazole-bridged dimer and trimers.

Click chemistry has become a very popular and efficient concept for synthetic chemists for the construction of new molecules. Among the click chemistry approaches known to date, it is undoubted that the copper-catalyzed alkyne-azide 1,3-dipolar cycloaddition (CuAAC) has played a key role. Such reactions in general offer virtually unlimited possibilities to prepare new molecules for $e.g$. materials science applications. As such, the synthesis of porphyrin–fullerene conjugates obtained via CuAAC are summarized within the present review article.

With the increased risk of infectious disease transmissions, photodynamic inactivation of some microorganisms for antimicrobial applications has been extensively studied in recent years. In this article, we describe the synthesis of novel photo-bactericidal materials by grafting propargylated 5,10,15,20-tetra(4-pyridyl)porphyrin on kraft pulp fibers. The grafting was carried out by a Huisgen’s 1,3-dipolar azide-alkyne cycloaddition reaction. This material has been investigated for its antibacterial properties against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. An interesting photo-bactericidal activity was shown: this material can be used to limit the growth of bacteria on surfaces and the formation of biofilms.

The synthesis and characterization of novel asymmetric zinc(II) phthalocyanines (4–9) and their linking through peripheral and nonperipheral positions on the phthalocyanine ring via click coupling to alkyne-functionalized 2,3,6,7,10,11-hexakis(prop-2-ynyloxy)triphenylene core are described for the first time. These phthalocyanines (Pcs) (4–12) were characterized by elemental analysis and different spectroscopic techniques such as UV-vis, ¹H-NMR, FT-IR and mass spectroscopy. Furthermore, the utilization of thin films of novel Pcs as a sensitive layer for detection of lung cancer from exhaled human breath at room temperature under exposure to marker volatile organic compounds (VOCs) are presented. The developed sensors were tested for acetone, ethanol, $n$-hexane, toluene, chloroform and isoprene in a range of 300–14560 ppm. The obtained results have confirmed the possibility of utilization of Pc-based Surface Acoustic Wave (SAW) sensors for medical diagnosis based on exhaled breath analysis.

Phthalocyanines (Pcs) are near-infrared photosensitizers with therapeutic potential for the treatment of bacterial infections and cancer. However, their clinical utility has been hindered by poor solubility in biological fluids, lack of specificity, and limited clearance from affected tissues. Glycosylated Pcs have the potential to overcome these issues by providing increased solubility and tumor specific targeting. However, reliable methods for their synthesis remains challenging. Here we present our first approach towards the synthesis of a series of silicon (IV) phthalocyanine conjugates bearing axial carbohydrate ligands (CPcCs). The novelty of our approach lies in the installation of axial alkyne ligands which can be functionalized with readily accessible acetyl protected azido glycosides, thus providing a modular approach for the synthesis of these complex macromolecules.

Alkyne-terminated Co phthalocyanine (CoPc) derivatives are linked to reduced graphene oxide nanosheets (GONS) via click chemistry and the conjugates are used for the electrocatalytic oxidation of 2-mercaptoethanol. CoPc derivatives where the alkyne group is separated from the Pc ring by an aliphatic and benzene ring (complex 3) showed the best catalytic activity (in terms of oxidation potential) in comparison to when only aliphatic chains were employed without the benzene ring (complex 2) and when there were no substituents (complex 1). The anodic oxidation of 2-mercaptoethanol on 3-GONS (linked) occurred at the least positive oxidation potential (-0.22 V vs. Ag|AgCl). 3-GONS (linked) was found to have the highest sensitivity with the lowest limit of detection of 0.08 $\mu$M. When the CoPc derivative and GONS were not linked but placed sequentially on the electrode, the electrocatalytic activity (in terms of LOD) was poorer than when linked. The electrodes modified with CoPc clicked to GONS are highly promising electrochemical sensors in terms of stability, sensitivity, good catalytic activity and ease of fabrication.

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 novel heteroditopic porphyrin-based ion pair receptor with four ureas and four triazoles on the same side of the porphyrin ring was synthesized through click chemistry. This receptor showed high affinity to complex with the ion pairs KCl, NaCl and NH₄Cl in 1:1 binding stoichiometries with association constants of 2.48 (± 0.43) × 10⁴, 1.06 (± 0.02) × 10⁵, and 1.97 (± 0.04) × 10⁵ M${}^{-1}$, respectively. After complexation with the ion pairs, fluorescence quenching of the porphyrin was observed, which enables its potential applications in ion detection.