Polymer nanocomposites based on functionalized carbon nanotubes

2.3. Ionic Liquids (ILs) 5374 2.4. Complexation Reactions on Oxidized CNTs 5375 2.5. Halogenation 5376 2.6. Cycloaddition Reactions 5377 2.7. Radical Additions 5379 2.8. Nucleophilic Additions 5381 2.9. Electrophilic Additions 5381 2.10. Electrochemical Modifications 5381 2.11. Plasma-Activation 5381 2.12. Mechanochemical Functionalizations 5382 3. Noncovalent Interactions 5382 3.1. Polynuclear Aromatic Compounds 5382 3.2. Interactions with Other Substances 5384 3.3. Interactions with Biomolecules 5385 4. Endohedral Filling 5386 4.1. Encapsulation of Fullerenes 5386 4.2. Encapsulation of Organic Substances 5387 4.3. Encapsulation of Inorganic Substances 5387 5. Decoration of CNTs with Metal Nanoparticles 5388 5.1. Covalent Linkage 5388 5.2. Direct Formation on Defect Sites 5388 5.3. Electroless Deposition 5388 5.4. Electrodeposition 5389 5.5. Chemical Decoration 5390 5.6. Deposition of Nanoparticles onto CNTs 5391 5.7. π-π Stacking and Electrostatic Interactions 5391 6. Concluding Remarks 5392 7. Acknowledgments 5392 8. References 5392

Current progress on the chemical modification of carbon nanotubes.

A Graphene Hybrid Material Covalently Functionalized with Porphyrin: Synthesis and Optical Limiting Property

A novel graphene oxide−doxorubicin hydrochloride nanohybrid (GO−DXR) was prepared via a simple noncovalent method, and the loading and release behaviors of DXR on GO were investigated. An efficient loading of DXR on GO as high as 2.35 mg/mg was obtained at the initial DXR concentration of 0.47 mg/mL. The loading and release of DXR on GO showed strong pH dependence, which may be due to the hydrogen-bonding interaction between GO and DXR. The fluorescent spectrum and electrochemical results indicate that strong π−π stacking interaction exists between them.

High-Efficiency Loading and Controlled Release of Doxorubicin Hydrochloride on Graphene Oxide

Porphyrins and phthalocyanines have outstanding chemical and thermal stability. The macrocyclic structure and chemical reactivity of tetrapyrroles offers architectural flexibility and facilitates the tailoring of chemical, physical and optoelectronic parameters. The specific optical properties of the tetrapyrrole macrocycle combined with the synthetic methodologies now available and the already available theoretical and spectroscopic knowledge on their optical behavior make porphyrins a target of choice for this area. They are versatile organic nanomaterials with a rich photochemistry and their excited state properties are easily modulated through conformational design, molecular symmetry, metal complexation, orientation and strength of the molecular dipole moment, size and degree of conjugation of the π-systems, and appropriate donor-acceptor substituents. Here we review the structural chemistry and optical properties of recently synthesized porphyrin derivatives that offer potential for nonlinear optical (NLO) applications and complement existing studies on phthalocyanines. Classes of interest include the classic A4 symmetric tetrapyrroles, while optimized systems include push-pull porphyrins, oligomeric and supramolecular self-assembled systems, films and nanoparticle systems, and highly conjugated porphyrin arrays.

Nonlinear Optical Properties of Porphyrins

Novel covalently porphyrin-functionalized single-walled carbon nanotubes (SWNTs) have been synthesized by the reaction of SWNTs with in situ generated porphyrin diazonium compounds. The resulting nanohybrid was characterized by spectroscopic (UV-Vis-NIR, FTIR and Raman) and microscopic (TEM and AFM) methods. The Raman and absorption spectroscopy data showed that the electronic properties of the modified tubes were mostly retained, without damaging their one-dimensional electronic properties. The fluorescence from the porphyrin moiety was almost completely quenched by SWNTs, indicating that the unique direct linkage mode facilitated the effective energy and electron transfer between the excited porphyrin moiety and the extended π-system of SWNTs. This novel nanohybrid material also exhibited excellent optical limiting properties.

Covalently porphyrin-functionalized single-walled carbon nanotubes: a novel photoactive and optical limiting donor–acceptor nanohybrid

Optical limiters are employed to protect sensitive optical components or eyes from laser-induced damage. [1,2] They have lower transmittance for high-intensity or fluence laser input while they keep a high linear transmittance. Many works have concentrated on creating ideal optical limiting devices by exploiting passive limiting mechanisms such as nonlinear absorption (multiphoton absorption, reverse saturable absorption (RSA)), nonlinear refraction (electronics or thermal effects), and nonlinear light scattering. Both single-walled carbon nanotube (SWNT) and multiwalled carbon nanotube (MWNT) suspensions have been reported to have strong optical limiting effects in the nanosecond regime, which arise from strong nonlinear light scatterings due to the creation of new scattering centers consisting of ionized carbon microplasmas and solvent microbubbles. [3–9] To promote their optical limiting effects, the optical nonlinear media with other optical nonlinear processes (e.g., two-photon absorption or RSA) have been blended with carbon nanotubes. [10,11] The association of SWNTs with organic chromophores having multiphoton absorption processes was recently shown to be a promising approach to achieve optical limiting systems with broad temporal and spectral responses. [10] Carroll et al. [11] also reported an enhanced nonlinear transmittance obtained by a RSA dye blended with carbon nanotubes. Recently, Blau et al. [12] presented a study on nonlinear optical characterization of stable porphyrin/SWNT composite solutions obtained by non-covalent bonding between the carbon nanotubes and conjugated tetraphenylporphyrin molecules. However, little research has been carried out on optical limiting effects of covalently functionalized SWNTs with reverse saturable absorbents. Vivien et al. [5] predicted that further optimizations of the optical limiting performances of carbon nanotubes may be achieved by the cumulative influences of different nonlinear effects arising from functionalized carbon nanotubes with reverse saturable absorbents. Porphyrins are often used as visible chromophores to decorate the surfaces of semiconductor and metal nanoparticles, and they are also promising candidates for applications in optical limiters owing to their large RSA in the visible even near-infrared wavelength range. [13–15] Furthermore, an effective energy or electron transfer may exist in the functionalized SWNTs with porphyrins. [16] The photoinduced electron transfer can result in a large optical limiting effect, which has been observed in the PVK-modified SWNTs system. [17,18] We also reported that a

Enhanced Optical Limiting Effects in Porphyrin‐Covalently Functionalized Single‐Walled Carbon Nanotubes

Novel β-cyclodextrin covalently modified single-walled carbon nanotubes have been synthesized via a ‘click’ coupling reaction. The product was fully characterized with Raman, FTIR, XRD, UV-Vis-NIR spectra as well as TEM and TGA measurements. The effective functionalization via ‘click’ coupling has set up a facile and versatile route for modular preparation of SWNTs based functional materials. The inclusion complexation behavior of this artificial receptor with quinine has been investigated in aqueous solution by fluorescence spectroscopy.

Covalently β-cyclodextrin modified single-walled carbon nanotubes: a novel artificial receptor synthesized by ‘click’ chemistry

Increased optical nonlinearities of multi-walled carbon nanotubes covalently functionalized with porphyrin

Novel covalently porphyrin functionalized single-walled carbon nanotubes (SWNTs) were synthesized using carboxylic group functionalized carbon nanotubes (o-SWNTs) with meso-aniline substituted porphyrin. The structure and morphology of this SWNT nanohybrid material were fully characterized with FTIR, Raman, UV-Vis-NIR spectra as well as TGA and TEM measurements. The energy transfer efficiency from porphyrin to SWNTs and porphyrin fluorescence quenching mechanism were studied by means of steady state fluorescence and time-resolved fluorescence measurement. The fast and efficient electron transfer occurring in this nanohybrid illustrates that they can be utilized as a good candidate for light harvesting materials in molecular photonic devices and solar energy utilization.

Zhen Guo

Papers

Covalently porphyrin-functionalized single-walled carbon nanotubes: a novel photoactive and optical limiting donor–acceptor nanohybrid

Enhanced Optical Limiting Effects in Porphyrin‐Covalently Functionalized Single‐Walled Carbon Nanotubes

Covalently β-cyclodextrin modified single-walled carbon nanotubes: a novel artificial receptor synthesized by ‘click’ chemistry

Increased optical nonlinearities of multi-walled carbon nanotubes covalently functionalized with porphyrin

A nanohybrid material of SWNTs covalently functionalized with porphyrin for light harvesting antenna: synthesis and photophysical properties.