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The synthesis and characterization of a new asymmetric isoindigo-based semiconducting polymer design containing branched alkyl and linear hydroxyl side chains is reported.

Microplastic (MP) pollution is a global challenge that requires immediate mitigation practices. Monitoring is crucial for quantifying MPs, but their mitigation remains very challenging due to several factors, including the lack of selective materials to specific polymers, and the low sensitivity of the current detection techniques. In this work, we introduce a novel design for the selective detection of MPs through fluorescence spectroscopy by exploiting conjugated polymer nanoparticles (CPNs). Fluorescent diketopyrrolopyrrole nanoparticles were prepared by nanoprecipitation to incorporate peripheral hyaluronic acid to increase their affinity for various plastics. The affinity of the new ligand for various types of MPs was examined through several characterization techniques, including fluorescence spectroscopy and microscopy, nanoparticle tracking analysis and computational studies. The new CPN were shown to be highly fluorescent in the presence of typically abundant MPs, achieving very strong binding constants in the picomolar range. This very strong affinity for a broad family of plastics was found to be the results of cooperative supramolecular effects and topographical affinity, as probed by advanced microscopy and in silico studies. Furthermore, the new affinity probes were shown to be highly selective for MPs, allowing for their detection in heterogeneous samples, including soil debris and other organic contaminants. The new materials design introduced in this work constitute a promising platform for the development of novel MP detection devices directly useable at the point of collection. Moreover, it opens new avenue for the mitigation of this environmental hazard through tailorable materials.

Incorporation of directing amide groups has been shown to facilitate the topochemical polymerization of 1,3-butadiyne (diacetylene) groups in noncrystalline phases such as gels, amorphous solids, and liquid crystals. It remains challenging to polymerize 1,3-butadiyne-containing alkylthiolate ligands within their self-assembled monolayers on gold nanoparticles (AuNPs), which enhances their stability and adds new optical and electronic properties. Especially smaller AuNPs of sizes below 5 nm in diameter have been reported to display sluggish photopolymerization and are susceptible to photodegradation under UV irradiation. To probe the effectiveness of the amide-directed photopolymerization of 1,3-butadiyne ligands, small AuNPs in the 2-4 nm range were synthesized that contain alkylthiolate ligands with and without amide and 1,3-butadiyne groups. Their photopolymerization and photostability were studied by transmission electron microscopy (TEM), UV-vis spectroscopy, and Raman spectroscopy. AuNP with amide-free 1,3-butadiyne ligands templated the polymerization of the 1,3-butadiyne ligands but fused to large and insoluble particles during the polymerization process. AuNPs with ligands containing both 1,3-butadiyne and amide groups polymerized significantly faster, which slowed down photodegradation. A UV irradiation (254 nm and 176 W/m

Recent advances in the design and preparation of electroactive materials, particularly semiconducting and conductive polymers, have resulted in the creation of novel organic electronics with advanced functionality and performance competitive with that of devices made of silicon. With an increasing number of organic and printed electronics being engineered and produced at a larger scale, the environmental cost of the final organic electronic devices (life cycle, environmental impact, etc.) needs to be considered. While e-waste is already a growing global problem, improving the sustainability of emerging electronics through a careful materials selection is highly desirable. In this work, we explore the use of shellac as a sustainable greener dielectric material in organic field-effect transistors (OFET). A careful examination of shellac in combination with diketopyrrolopyrrole-based semiconducting polymers was performed on rigid substrates through AFM and the fabrication of thin film transistors. All devices made from this green dielectric showed good performance and device characteristics. Building from this investigation, shellac was further integrated with paper substrates to fabricate paper-based thin film transistors. Thin film samples based on shellac on both silicon wafer and paper substrates were characterized by atomic force microscopy to investigate solid-state morphology of shellac and selected semiconducting materials. Through careful optimization of the device architecture and processing time, device characteristics and performances on paper substrates (average charge mobilities and on/off current ratios) were comparable to those of devices prepared on silicon wafers, confirming that shellac, in combination with organic semiconducting polymers, can be an advantageous dielectric material to be used for the fabrication of greener and sustainable thin film electronics from renewable feedstocks and components.

The relationship between backbone fluorination and the solid-state properties of semiconducting polymers was evaluated to unveil the impact on thermomechanical properties.

In this article, a new series of conjugated polymers based on a low-cost, easily accessible vat dye called Vat orange 1 or 2,9-dibromo-dibenzo[b,def]chrysene-7,14-dione have been prepared. This compound was made electron-donating by reducing and alkylating the ketone groups into alkoxy groups, allowing the introduction of solubilizing, branched alkyl chains at the 7 and 14 positions. Polymerization reactions using Suzuki–Miyaura coupling with 6,6′-isoindigo, 3,6-di-2-thienyl-pyrrolo[3,4-c]pyrrole-1,4-dione (DPP) and 4,7-dithieno-2,1,3-benzothiadiazole (TBT) yielded three donor–acceptor polymers with bandgap values ranging from 1.61 to 1.86 eV. Field-effect transistors (OFETs) and organic solar cells (OSCs) were fabricated and hole mobility values of up to 3.62 × 10−4 cm2 V−1 s−1 and a maximum power conversion efficiency of 1.2% were measured, respectively.

The optoelectronic properties of a given conjugated polymer depend on the chain rigidity and more importantly local chain planarity. The local backbone planarity determines the conjugation length as large twists result in break of conjugation.

Summary Polymer semiconductors have shown distinct promise for the development of human-integrated electronics, owing to their solution processability and mechanical softness. However, numerous functional properties required for this application domain face synthetic challenges to being conveyed onto conjugated polymers and thus combined with efficient charge-transport properties. Here, we develop a “click-to-polymer” (CLIP) synthesis strategy for conjugated polymers, which uses a click reaction for the facile and versatile attachment of diverse types of functional units to a pre-synthesized conjugated-polymer precursor. With four types of functional groups, we show that functionalized polymers from this CLIP method can still retain good charge-carrier mobility. We take two realized polymers to showcase a photopatternable property and a biochemical sensing function, both of which advance the state of the art of realizing these two types of functions on conjugated polymers. We expect that the expanded use of this synthesis approach can largely enrich the functional properties of conjugated polymers.

Intrinsic mechanical properties of sub-100 nm thin films are markedly difficult to obtain, yet an ever-growing necessity for emerging fields such as soft organic electronics. To complicate matters, the interfacial contribution plays a major role in such thin films and is often unexplored despite supporting substrates being a main component in current metrologies. Here we present the shear motion assisted robust transfer technique for fabricating free-standing sub-100 nm films and measuring their inherent structural–mechanical properties. We compare these results to water-supported measurements, exploring two phenomena: 1) The influence of confinement on mechanics and 2) the role of water on the mechanical properties of hydrophobic films. Upon confinement, polystyrene films exhibit increased strain at failure, and reduced yield stress, while modulus is reduced only for the thinnest 19 nm film. Water measurements demonstrate subtle differences in mechanics which we elucidate using quartz crystal microbalance and neutron reflectometry., Intrinsic mechanical properties of sub-100 nm thin films are markedly difficult to obtain, yet an ever-growing necessity for emerging fields such as soft organic electronics. Here, the authors present a shear motion assisted transfer technique for fabricating free-standing sub-100 nm thin films and measuring their inherent structural–mechanical properties.

The semicrystalline microstructures of donor–acceptor conjugated polymers strongly impact their optoelectronic properties. The control of the microstructure relies on the understandings of the crys...

Flexible pressure sensors with self-healing abilities for wearable electronics are being developed, but generally either lack autonomous self-healing properties or require sophisticated material processing methods. To address this challenge, we developed flexible, low-cost and autonomously self-healing capacitive sensors using a crosslinked poly(dimethylsiloxane) through metal-ligand interactions processed into thin films via slot-die coating. These films have excellent self-healing properties, approximately 1.34 × 105 μm3 per hour at room temperature and 2.87 × 105 μm3 per hour at body temperature (37 °C). Similarly, no significant change in capacitance under bending strain was observed on these flexible thin-films when assembled on poly(ethyleneterephthalate) (PET) substrates; capacitors showed good sensitivity at low pressure regimes. More importantly, the devices fully recovered their sensitivity after being damaged and healed, which is directly attributed to the rapid and autonomous self-healing of the dielectric materials.

The synthesis and characterization of six new N-annulated perylene diimide (N-PDI) molecules consisting of different alkyl-based heteroatom and waxy infused sidechains is reported. Amino, urea, quaternary methyl ammonium, iminopyridine, hexadecyl and pyridine moieties were all appended to the pyrrolic N-position of N-annulated PDI. These N-PDI derivatives have been synthesized using facile SN2 chemistry resulting in high yields and without the need for purification via column chromatography. To further demonstrate the functional diversification offered by N-PDI we appended a cyano group to the 6,7-bay positions opposite the N-annulation and tested its capability for use in organic field effect transistor devices. Complete characterization of these N-PDI derivatives was completed using UV-Vis spectroscopy, cyclic voltammetry and solubility determination to observe how the appended sidechains have affected the structure-properties relationships of N-PDI derivatives.

Imide-functionalized organic monomers and polymers are attractive in organic optoelectronic devices due to the strong electron-withdrawing ability of the carbonyl units. We report the synthesis of ...

Intrinsic porosity in polymeric materials arises from the formation of a continuous network of interconnected voids and is a direct consequence of the shape and rigidity of the molecular building b...

The glass transition temperature (Tg) of conjugated polymers is a crucial physical parameter that governs their mechanical and electrical properties for applications from sensor technology to skin-...

A rational side-chain engineering was performed on a semicrystalline semiconducting conjugated polymer based on diketopyrrolopyrrole (DPP) to incorporate metal-chelating moieties without disruption of the π-conjugation. Specifically, a benzimidazole pyridine-based pincer ligand (MeBZIMPY), known to easily coordinate with M(II) metal centers, was inserted into the conjugated polymer and the effect of Fe(II) coordination on the optical properties was probed by absorption spectroscopy. Moreover, a careful analysis was performed on the metallopolymer in the solid state by grazing incidence X-ray diffraction and atomic force microscopy to evaluate the effect of coordination on the nanoscale morphology and chain packing. Coordination of Fe was directly confirmed by X-ray fluorescence spectroscopy and X-ray near edge absorption spectroscopy experiments. The resulting semiconducting metallopolymer was shown to possess a good solubility in common organic solvents after complexation and a smooth morphology at the nanoscale. The electronic properties of the new metallopolymer were evaluated through fabrication of organic field-effect transistors (OFETs). Interestingly, coordination of Fe(II) by the pincer ligand-containing DPP polymer was shown to enhance the charge mobility in organic field-effect transistors, going from 0.84 to 1.18 cm2 V−1 s−1 upon coordination, which can be directly attributed to the influence of the metal complex on the solid-state morphology. The direct coordination of Fe(II) through pincer ligands is a promising strategy to enhance the charge transport and modulate the optoelectronic properties of π-conjugated polymers without the use of π-conjugation breaking units and/or multi-step synthesis.

Short oligomeric species end-capped with imine-based ligands can generate intrinsic autonomous self-healable soft polymers upon metal coordination, allowing for the preparation of materials that can be easily fine-tuned in terms of mechanical properties and robustness. To develop a rational understanding of the self-healing mechanism on this system, an investigation of the fine-tuning of the self-healing efficiency by evaluating the metal used to induce crosslinking was performed. Moreover, the counter-ion used in the crosslinking system was also evaluated in order to probe its influence on the final thermomechanical properties. The resulting self-healing polymers were characterized by multiple techniques, including UV-Vis spectroscopy, tensile-strain pull testing, and shear rheology. The metal was shown to have a significant influence on the thermomechanical properties of the system, which can be directly attributed to the coordination geometry (crosslinking density) and bond strength. Moreover, the choice of the counterion used for crosslinking also showed a significant influence on the mechanical properties and self-healing efficiency. These results highlight the versatility of the end-capped polydimethylsiloxane (PDMS)-based system and provide valuable insights for the future development of self-healing polymers that can be produced on a large scale through solution processing, for a wide variety of applications.

Despite having favorable optoelectronic and thermomechanical properties, the wide application of semiconducting polymers still suffers from limitations, particularly with regards to their processing in solution which necessitates toxic chlorinated solvents due to their intrinsic low solubility in common organic solvents. This work presents a novel greener approach to the fabrication of organic electronics without the use of toxic chlorinated solvents. Low-molecular-weight non-toxic branched polyethylene (BPE) is used as a solvent to process diketopyrrolopyrrole-based semiconducting polymers, then the solvent-induced phase separation (SIPS) technique is adopted to produce films of semiconducting polymers from solution for the fabrication of organic field-effect transistors (OFETs). The films of semiconducting polymers prepared from BPE using SIPS show a more porous granular morphology with preferential edge-on crystalline orientation compared to the semiconducting polymer film processed from chloroform. OFETs based on the semiconducting films processed from BPE show similar device characteristics to those prepared from chloroform without thermal annealing, confirming the efficiency and suitability of BPE to replace traditional chlorinated solvents for green organic electronics. This new greener processing approach for semiconducting polymers is potentially compatible with different printing techniques and is particularly promising for the preparation of porous semiconducting layers and the fabrication of OFET-based electronics.

Correction for ‘Asymmetric side-chain engineering in semiconducting polymers: a platform for greener processing and post-functionalization of organic electronics’ by Madison Mooney et al., Polym. Chem., 2023, https://doi.org/10.1039/d2py01244h.

Copyright © 2019 American Chemical Society. A nanoprecipitation procedure was utilized to prepare novel diketopyrrolopyrrole-based semiconducting polymer nanoparticles (SPNs) with hyaluronic acid (HA) and polysorbate 80. The nanoprecipitation led to the formation of spherical nanoparticles with average diameters ranging from 100 to 200 nm, and a careful control over the structure of the parent conjugated polymers was performed to probe the influence of π-conjugation on the final photophysical and thermal stability of the resulting SPNs. Upon generation of a series of novel SPNs, the optical and photophysical properties of the new nanomaterials were probed in solution using various techniques including transmission electron microscopy, dynamic light scattering, small-angle neutron scattering, transient absorption, and UV-vis spectroscopy. A careful comparison was performed between the different SPNs to evaluate their excited-state dynamics and photophysical properties, both before and after nanoprecipitation. Interestingly, although soluble in organic solution, the nanoparticles were found to exhibit aggregative behavior, resulting in SPNs that exhibit excited-state behaviors that are very similar to aggregated polymer solutions. Based on these findings, the formation of HA- and polysorbate 80-based nanoparticles does not influence the photophysical properties of the conjugated polymers, thus opening new opportunities for the design of bioimaging agents and nanomaterials for health-related applications.

We show here that non-network metallopolymers can possess intrinsic microporosity stemming from contortion introduced by metallocene building blocks. Metallopolymers constructed from ferrocenyl building blocks linked by phenyldiacetylene bridges are synthesized and possess BET surface areas up to 400 m2/g. As solubility imparted by pendant groups reduces porosity, copolymerization is used to simultaneously improve both accessible surface area and solubility. Spectroscopic analysis provides evidence that mixed valency between neighboring ferrocenyl units is supported in these polymers.

Glioblastoma is one of the most aggressive types of cancer with median survival of only 15 months. Successful therapy is hampered by the existence of treatment resistant populations of stem-like tumour initiating cells (TICs) and poor blood-brain barrier drug penetration. Therapies capable of effectively targeting the TIC population are in high demand. Here, we synthesize spherical diketopyrrolopyrrole (DPP)-based conjugated polymer nanoparticles (CPNs) with an average diameter of 109 nm. The CPN were designed to include fluorescein-conjugated hyaluronic acid (HA), a ligand for the CD44 receptor present on one population of TICs. We demonstrate blood-brain barrier permeability of this system and concentration and cell cycle phase-dependent selective uptake of HA-CPNs in CD44 positive GBM-patient derived cultures. Interestingly, we found that uptake alone decreases stemness, invasive properties and proliferation of the CD44-TIC population in zebrafish PDX models in vivo. This study is the first to show surface moiety-driven selectivity of conjugated polymer nanoparticles in targeting TIC populations in brain cancer.

Glioblastoma is one of the most aggressive types of cancer with median survival of only 15 months. Successful therapy is hampered by the existence of treatment resistant populations of stem-like tumour initiating cells (TICs) and poor blood-brain barrier drug penetration. Therapies capable of effectively targeting the TIC population are in high demand. Here, we synthesize spherical diketopyrrolopyrrole (DPP)-based conjugated polymer nanoparticles (CPNs) with an average diameter of 109 nm. The CPN were designed to include fluorescein-conjugated hyaluronic acid (HA), a ligand for the CD44 receptor present on one population of TICs. We demonstrate blood-brain barrier permeability of this system and concentration and cell cycle phase-dependent selective uptake of HA-CPNs in CD44 positive GBM-patient derived cultures. Interestingly, we found that uptake alone decreases stemness, invasive properties and proliferation of the CD44-TIC population in zebrafish PDX models in vivo. This study is the first to show surface moiety-driven selectivity of conjugated polymer nanoparticles in targeting TIC populations in brain cancer.

Organic field-effect transistors (OFETs) are at the forefront of next generation electronics. This class of devices is particularly promising due to the possibility of fabrication on mechanically compliant and conformable substrates, and potential manufacturing at large scale through solution deposition techniques. However, their integration in circuits, especially using stretchable materials, is still challenging. In this work, the design and implementation of a novel structure for an integrated CMOS readout circuitry is presented and its fundamentals of operation are provided. Critical for sensing applications, the readout circuitry described is highly linear. Moreover, as several sources of mismatch and error are present in CMOS and OFET devices, a calibration technique is used to cancel out all the mismatches, thus delivering a reliable output. The readout circuit is implemented in TSMC 0.18μm CMOS technology in order to verify the theory. The maximum total power consumption in the proposed readout circuit is less than 571μW, while fully loaded calibration circuit consumes a power less than 153μW, making it suitable for sensors applications. Based on previously reported high mobility and stretchable semiconducting polymers, this new design and readout circuitry is an important step toward a broader utilization of OFETs and the design of stretchable sensors.

Molecular self-assembly through noncovalent interactions is a particularly efficient approach to fine-tune the optoelectronic and photophysical properties of electroactive materials. In metal-ligand coordination polymers, the final properties of the assemblies are directly related to the nature of the metal-ligand interaction. To probe for such influence on the photophysical properties of electroactive materials, a series of coordination polymers based on a well-known organic dye, diketopyrrolopyrrole, was prepared through coordination of a terpyridine-containing monomer with various metal sources, including iron, cobalt, zinc, and manganese. The resulting supramolecular polymers were characterized through multiple techniques, including UV-vis and fluorescence spectroscopy, time-correlated single-photon counting, and femtosecond transient absorption spectroscopy to reveal the impact of the metal source on the final photophysical properties of coordination polymers. As expected, important variations were found between different coordination polymers in terms of absorption, fluorescence kinetics, and electron transfer rate. While iron and cobalt-containing polymers showed ultrafast electrons transfer rates, assemblies from manganese were shown to be much less efficient, confirming the importance of metal centers. This detailed fundamental study unravels some important relationships between metal-ligand interactions, supramolecular self-assembly, and photophysical properties, ultimately leading to new avenues for the design of functional polymers based on organic dyes.

Thermomechanical properties of polymers highly depend on their glass transition temperature (T g). Differential scanning calorimetry (DSC) is commonly used to measure T g of polymers. However, many conjugated polymers (CPs), especially donor–acceptor CPs (D–A CPs), do not show a clear glass transition when measured by conventional DSC using simple heat and cool scan. In this work, we discuss the origin of the difficulty for measuring T g in such type of polymers. The changes in specific heat capacity (Δc ₚ) at T g were accurately probed for a series of CPs by DSC. The results showed a significant decrease in Δc ₚ from flexible polymer (0.28 J g⁻¹ K⁻¹ for polystyrene) to rigid CPs (10⁻³ J g⁻¹ K⁻¹ for a naphthalene diimide‐based D–A CP). When a conjugation breaker unit (flexible unit) is added to the D–A CPs, we observed restoration of the Δc ₚ at T g by a factor of 10, confirming that backbone rigidity reduces the Δc ₚ. Additionally, an increase in the crystalline fraction of the CPs further reduces Δc ₚ. We conclude that the difficulties of determining T g for CPs using DSC are mainly due to rigid backbone and semicrystalline nature. We also demonstrate that physical aging can be used on DSC to help locate and confirm the glass transition for D‐A CPs with weak transition signals. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 1635–1644

Polydiacetylenes are well-established one-dimensional organic semiconductors that have been generated by photochemical and thermal polymerizations of diacetylenes in single crystals, gel phases, thin films, and membranes. Their formation in mesophases, such as liquid crystals, has been surprisingly little studied although higher-ordered mesophases should support the topochemical polymerization of diacetylenes (1,3-butadiyne groups) and may give access to large domains of uniformly aligned materials. The polymerization of diacetylenes in a mesophase may also increase the stability of the self-assembled supramolecular structure. Here, the dye and discotic mesogen tetraazaporphyrin was decorated with eight diacetylene-containing alkyl chains to probe its mesomorphism and conversion into multifunctional polydiacetylene materials. While the incorporation of diacetylene groups supports columnar mesomorphism, successful photopolymerization required the presence of directing amide groups that suppressed columnar in favor of nematic mesomorphism. Still, the polymerization of the nematic mesophase generated a soluble nematic polydiacetylene of significantly higher molecular weight (

A new approach for improving the mechanical properties of semiconducting polymers was established via physical combination of a diketopyrrolopyrrole-based conjugated polymer with a low-molecular-we...

A new methodology to covalently cross-link π-conjugated polymers by generating π-conjugated bridges was developed through the topochemical polymerization of 1,3-butadiyne moieties. Isoindigo-based ...

Backbone engineering was performed on highly rigid semiconducting polymers to include diketopyrropyrrole (DPP) units combined with pyrazine-containing moieties. These new moieties were shown to improve backbone planarity through a conformational locking effect between nitrogen and sulfur atoms. The new polymers, characterized by various techniques, were shown to possess a highly crystalline and smooth solid-state morphology, optimal for charge transport. To verify the potential of the new semiconductor for organic electronics, a series of organic field-effect transistors was fabricated. Interestingly, the new polymer was shown to possess a charge mobility of 0.27 cm² V⁻¹ s⁻¹ and on/off current ratio of 10⁷, which is an improvement when compared to a thiophene analogue. More importantly, the polymer led to devices with high stability, with a retention of device characteristics when exposed to the same bias stress comparable to a benchmark reference polymer. The utilization of pyrazine-containing moieties as a conformational lock is a promising strategy to achieve a high performance conjugated polymer in a simple manner. Moreover, their utilization in bottom-gate bottom-contact devices highlights the potential of this new semiconductor for fully printed high-performance electronics.

Diketopyrrolopyrrole and isoindigo are commercially important dyes that have recently found broad application as electron acceptor and light-absorbing groups in organic semiconductors. Their self-assembly into specific supramolecular structures to control optoelectronic properties has been hampered by limited options for substitution and their high propensity for crystallization. Reported here is a molecular design that directs self-assembly into previously elusive columnar mesophases of π-π stacking cores. Although attachment of bis(trisoctyloxyphenyl)-1,3,5-triazine groups to both ends of diketopyrrolopyrrole-thiophene and isoindigo cores generated mesomorphic dyes of similar overall shapes and dimensions, distinct differences in their mesomorphism and optoelectronic properties were observed.

Intermolecular interactions between tetraazaporphyrin (TAP) macrocycles are less dominated by π-π stacking interactions than interactions between their larger phthalocyanine derivatives. Consequently, the self-organization and -assembly of TAPs is more widely altered by changes to the type of complexed metal ion and substitution pattern. Presented here are different molecular designs for mesomorphic and amphiphilic TAPs that could be cross-linked by “click” chemistry and by the photo and thermal polymerization of diacetylene groups. All compounds were studied by polarized optical microscopy, thermal analysis, and X-ray diffraction to probe their (meso)phase structures and transitions and by the Langmuir-Blodget method to quantify their interfacial properties. Potential applications for these compounds include their use as active materials in sensors, functional coatings for metal oxide nanoparticles, and building blocks for dye nanoparticles. Topochemical Polymerization of a Nematic Tetraazaporphyrin Derivative to Generate Soluble Polydiacetylene Nanowires. M. Nazir Tahir, et al., 2019, Langmuir, 35(47) 15158−15167. Self-organization of Porphyrins and Phthalocyanines in two and three dimensions by S. Holger Eichhorn and Elmahdy Abdulhamied, in “Handbook of Porphyrin Science: Towards Tuned Properties of Porphyrinoids”, Vol. 42, Karl M. Kadish, Kevin M. Smith, Roger Guilard, Eds., World Scientific, Singapore, 2016, 173-232. Cross-linking of discotic tetraazaporphyrin dyes in 2 and 3 dimensions by “click” chemistry. Himadri Kayal, et al., 2013, J. Mater. Chem. C, 1(42), 7064-7072. Face- and edge-on orientations of octa-acid and -alcohol substituted tetraazaporphyrins in langmuir and Langmuir-Blodgett monolayers. M. M. Ahmida, et al., 2013, Soft Matter 9 (3), 811-9.