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Visual detection of analytes has been a significant challenge in the design and development of optical chemosensors. Sensing of analytes in aqueous solution by organic molecules has encountered some issues, such as poor water solubility and quenching of optical properties. In this study, a new category of smart dendritic macromolecules was designed and synthesized by functionalization of the poly(amidoamine) (PAMAM) dendrimer with spiropyran molecules to afford a photoluminescent dendritic structure (SP-PAMAM). Smart optical sensors were prepared by physical incorporation of four different oxazolidine derivatives containing hydroxyl and nitro substituted groups into the SP-PAMAM structure. Investigation of optical properties demonstrated photoinduced electron transfer (PET) between the spiropyran end group of SP-PAMAM and oxazolidine derivatives (in a concentration of about 0.0002 M), which can result in quenching of fluorescence emission of spiropyran photoswitch in the form of merocyanine (MC). Treatment of the oxazolidine-doped SP-PAMAM samples with metal ions resulted in changes in the PET mechanism (switching on or off), as observed in the case of Fe

Organic–inorganic hybrid composites have received much attention of scientists in the recent years due to the notable improvement of thermal properties without using of organic or inorganic nanoparticles. Hence, we have developed a facile strategy to prepare a 3D hybrid network based on silane materials and novolac resin via sol–gel process. At first step, novolac resin was prepared by general procedure with appropriate thermal properties and then modified with (3-chloropropyl)triethoxysilane (CPTES) to form MNR. In second step, to cure MNR and prepare hybrid composite structures, general amine-cured system and sol–gel process were applied to prepare MNH and MNSG samples, respectively. XRD analysis was used to support the formation of silane networks in hybrid samples. Investigation of thermal properties by DSC and TGA showed that cured samples had much higher thermal stability and char yield with respect to novolac and modified resin (MNR) originated from formation of 3D Si–O–Si network. Presented method limited some disadvantages of using nanoparticles such as aggregation and poor distribution. Such hybrid composites with high thermal stability have potential applications in advanced fields such industrial molds, coatings, adhesives and composites.

Stimuli-responsive polymers are an important class of advanced materials that have lots of applications in biochemistry, biomedicine, optical memory, and cell labeling. The physical and chemical properties of these materials and also their surrounding media could be varied in response to environmental excitation. Temperature-responsive polymers are a significant category of smart polymers, displaying phase separation and cloud points in response to temperature variations in the solution state. Controlling such responses with light has become an interesting research area, because of the advantages of light-responsive materials for the reversible control of the physical and chemical properties of media in systems with tunable intensities. Photochromic compounds are some of the most important light-responsive materials used for the light-control of temperature-responsivity in light- and temperature-responsive polymers. The incorporation of photochromic compounds, such as spiropyran, azobenzene, diarylethene, and spiroxazine, in temperature-responsive polymers results in reversible light-induced variations of lower critical solution temperatures, upper critical solution temperatures, and phase separation temperatures in such systems. The incorporation of o-nitrobenzyl ester photoactive compounds in temperature-responsive polymers can result in irreversible light-induced variations of these characteristics. These variations originate from light-induced polarity changes in the systems resulting from the responses of the light-responsive compounds. Controlling the thermo-responsivity of dual light- and temperature-responsive polymers using light illumination is the main focus of this study, which is beneficial for the development of new dual- or multi-responsive polymers with potential applications in drug- and gene-delivery systems.

Counterfeiting and inverse engineering of security and confidential documents, such as banknotes, passports, national cards, certificates, and valuable products, has significantly been increased, which is a major challenge for governments, companies, and customers. From recent global reports published in 2017, the counterfeiting market was evaluated to be $107.26 billion in 2016 and forecasted to reach $206.57 billion by 2021 at a compound annual growth rate of 14.0%. Development of anticounterfeiting and authentication technologies with multilevel securities is a powerful solution to overcome this challenge. Stimuli-chromic (photochromic, hydrochromic, and thermochromic) and photoluminescent (fluorescent and phosphorescent) compounds are the most significant and applicable materials for development of complex anticounterfeiting inks with a high-security level and fast authentication. Highly efficient anticounterfeiting and authentication technologies have been developed to reach high security and efficiency. Applicable materials for anticounterfeiting applications are generally based on photochromic and photoluminescent compounds, for which hydrochromic and thermochromic materials have extensively been used in recent decades. A wide range of materials, such as organic and inorganic metal complexes, polymer nanoparticles, quantum dots, polymer dots, carbon dots, upconverting nanoparticles, and supramolecular structures, could display all of these phenomena depending on their physical and chemical characteristics. The polymeric anticounterfeiting inks have recently received significant attention because of their high stability for printing on confidential documents. In addition, the printing technologies including hand-writing, stamping, inkjet printing, screen printing, and anticounterfeiting labels are discussed for introduction of the most efficient methods for application of different anticounterfeiting inks. This review would help scientists to design and develop the most applicable encryption, authentication, and anticounterfeiting technologies with high security, fast detection, and potential applications in security marking and information encryption on various substrates.

Counterfeiting of confidential documents has been a costly challenge for banks, companies, and customers. Encryption of invisible security marks, such as barcodes, quick response codes, and logos, in national or international confidential documents by high-security anticounterfeiting inks is the most significant solution for counterfeiting problems. Ecofriendly multi-color photoluminescent anticounterfeiting inks based on highly-fluorescent polymer nanoparticles functionalized with new oxazolidine derivatives were developed for the fast and facile encryption of security labels on cellulosic documents, such as paper currency, passport, and certificate. Depending on the polarity of functionalized polymer nanoparticles, a wide range of colors and fluorescence emissions were observed as a result of polar-polar interactions between the oxazolidine molecules and surface functional groups of the nanoparticles. The fluorescent polymer nanoparticles showed spherical, vesicular, and cauliflower-like morphologies resulted from different surface functional groups. Functional polymer nanoparticles displayed high stability and printability on cellulosic substrates due to hydrogen bonding interactions. The highly-fluorescent polymer nanoparticles were also used to prepare anticounterfeiting inks with different colors and fluorescence emissions. All the ecofriendly polymeric anticounterfeiting inks were loaded to stamps with specific marks, and then applied to different confidential documents. Printed labels displayed highly intense fluorescence emission in different colors (green, orange, pink, and purple depending on the matrix polarity) under UV irradiation (365 nm). These water-based multi-color fluorescent anticounterfeiting inks with highly intense, bright, and sensitive fluorescence emission have potential applications in encryption and authentication of security patterns.

Hear, three hybrid composites with high char yield and thermal stability were prepared form tetraethyl orthosilicate (TEOS)-modified epoxy resin (MER), (3-glycidyloxypropyl) trimethoxysilane (GPTES)-modified novolac resin (MNR), epoxidized novolac resin (ENR), and silica-grafted carbon nanotube (SFCNT) by a sol-gel method. The first class was prepared from MER and SFCNT. The second class was prepared from MER, MNR, and SFCNT. And the third class was prepared from MNR, ENR, and SFCNT. TEOS was used as covalent coupling agent in the sol-gel process. Results of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed successful modification of epoxy and novolac resins, modification of silica nanoparticles with (3-Aminopropyl)triethoxysilane (APTES), and also functionalization of CNT with amine-modified silica nanoparticles. Results of thermogravimetric analysis confirmed that the hybrid composite containing 4 wt% of SFCNT, MNR, and ENR shows the highest char yield of 58.4%. The hybrid composite containing 4 wt% of SFCNT and MER shows the highest degradation temperature of 442.7 °C. Finally, the hybrid composite formed from 4 wt% of SFCNT, MER, and MNR shows degradation temperature of 439.0 °C and char yield of 47.2%. Microscopic images and X-ray diffraction results confirmed attachment of silica particles at the surface of CNT by chemical bonding.

Symmetric tri-block copolymer as P(DMAEMA-co-CuA)-b-PDMS-b-P(DMAEMA-co-CuA) was synthesized by atom transfer radical polymerization (ATRP) in which PDMS was used as bis-functionalized initiator. Moreover, PDMAEMA as multi-responsive hydrophilic segment was copolymerized with coumarin moieties as photocrosslinking agent. Variation of the ratio of hydrophilic/hydrophobic segments in block copolymers was resulted in different morphologies including snowman-like, hollow, spherical, and cubic structures where the morphology was affected by pH of media. The size of self-assembled tri-block copolymers was changed toward external stimuli including temperature, CO2 bubbling, and pH due to multi-responsivity of PDMAEMA block. The presence of photoactive coumarin molecules in hydrophilic PDMAEMA block was utilized for stabilizing the morphology in the self-assembled particles upon UV light irradiation (365 nm). Photocrosslinking of self-assembled particles by UV light-induced dimerization of coumarin molecules via [2π + 2π] cycloaddition reaction was investigated by spectroscopy and microscopy methods, and results indicated that morphology of the particles was stabilized after photocrosslinking. Also, the rate of coumarin dimerization was affected by its concentration, and size and morphology of the particles. According to the advantages of developed self-assembly system considering various UV-crosslinkable morphologies and multi-responsiveness, these structures have potential application in drug delivery systems for controlled release of doxorubicin (DOX).

Multi-responsive polymer assemblies are a significant class of smart polymers with potential applications in drug-delivery and gen-delivery systems. Poly(dimethylaminoethyl methacrylate) (PDMAEMA) is among the most applicable multi-responsive polymers that changes its physical and chemical properties in response to temperature, pH, and CO2. Herein, different types of light-, temperature-, pH-, and CO2-responsive polymer assemblies were developed based on multi-responsive PDMAEMA and hydrophobic poly(methyl methacrylate) blocks. In addition, spiropyran was incorporated at the chain ends by using spiropyran-initiated atom transfer radical polymerization method. Novel smart drug-delivery systems were developed by self-assembly of these amphiphilic block copolymers to micellar morphologies in aqueous media. Dynamic light scattering results showed that size of the polymer assemblies changed in response to pH variations (from 5 to 9), temperature changes (above the lower critical solution temperature (LCST) of PDMAEMA), and also UV light irradiation (wavelength of 365 nm). The LCST of PPDMAEMA showed a shift from 53 to 60 °C after isomerization of the SP to MC form, as a result of increase of polarity and water-solubility. The PDMAEMA block results in responsivity of the prepared copolymer assemblies to CO2, which display pH variation from 8–8.6 to 5–6 after 2 min of CO2 gas bubbling. All the multi-responsive micellar polymer assemblies showed various loading capacities and release profiles, and the DOX release can be controlled by pH, temperature, and light. The release efficiency is reached to 60–85% at pH 5.3, 80–90% at temperatures higher than the LCST of PDMAEMA (60 °C), and also 90–100% under UV light irradiation after 48 h. In summary, the multi-responsive polymer assemblies based on amphiphilic block copolymers containing spiropyran chain end groups in the current study have potential applications in smart drug-delivery systems, and offer controlling over the drug-release by different triggers, such as light irradiation, pH variation, and temperature change. A very low concentration of spiropyran molecules (one per polymer chain) showed light-controlling of drug-release from the assemblies with high efficiencies.

Dendritic-star supramolecular structure of poly(amidoamine)-g-[polystyrene-b-(2-(dimethylamino)ethyl methacrylate-co-11-((4-methyl-2-oxo-2H-chromen-7-yl)oxy)undecyl acrylate)] (PAMAM-g-P(St-b-(DMAEMA-co-CuA))) was synthesized via grafting-from atom transfer radical polymerization (ATRP) by using PAMAM-initiator as smart drug carrier. This structure consisted of multi-responsive unites of hydrophilic PDMAEMA regarding to pH change, temperature, and CO2 gas and the coumarin molecule as photocrosslinking agent. Photocrosslinking agent is efficient for controlling DOX release after dimerization under UV light. The chemical structure of samples was confirmed by proton nuclear magnetic resonance (1H NMR) and their molecular weight was studied by gel permeation chromatography (GPC). The change of hydrophilic length of PDMAEMA and pH media resulted in various morphologies including hollow sphere, snowman- and dumbbell-like particles. The morphology of supramolecular assemblies was not changed after photocrosslinking, which confirmed the structure stabilization under UV light irradiation of 365 nm. Fluorescence microscopy was confirmed the presence of fluoresce segments in self-assembled supramolecular structures. Dynamic light scattering (DLS) indicated that the size of supramolecular assemblies was changed through the response to external stimuli such as pH, temperature, and CO2 gas. The DOX release behavior was investigated in different conditions such as pH, temperature, and after photocrosslinking under UV light of 365 nm.

Photodetection of originality and authentication of security documents such as money, passport, bank note, and national card have been a significant challenge in recent decade. Using of advanced optical systems could remarkably reduce copy and counterfeiting of such national and international documents. Novel ecofriendly multi-color photoluminescent inks were developed for information encryption on cellulosic papers and optical authentication of confidential/original documents by synthesis of water-based latex nanoparticles modified with photoluminescent coumarin (blue emission) and two photochromic spiropyran derivatives (red and orange emissions). Some of the latexes with higher fluorescence emission were formulated to water-based inks, and then loaded to stamps with different marks for printing of quick response code, barcode, finger print, and other marks on cellulosic documents. All of the printed marks display ultra-bright blue, red, and orange fluorescence emissions upon UV irradiation, which have potential applications in encryption, security marking and optical authentication of confidential cellulose substrates.

Stimuli-responsive block copolymer assemblies are a significant class of smart materials extensively studied for advanced applications such as drug- and gen-delivery systems. Different types of light- and temperature-responsive polymer assemblies containing photochromic spiropyran chain end groups, temperature-responsive poly (N-isopropylacrylamide) (PNIPAM) block, and hydrophobic poly (methyl methacrylate) (PMMA) block were developed. These amphiphilic block copolymers with the ability of self-assembly to micellar structures were synthesized using spiropyran-initiated atom transfer radical polymerization. Regarding the hydrophilic fraction (0.5

The synthesis, spectral characterization and fluorescence studies of some novel substituted 8-chloro-3H-imidazo[4,5-a]acridine-11-carbonitriles are presented. The nucleophilic substitution of hydrogen in 5-nitrobenzimidazole derivatives occurs upon reaction with 2-(4-chlorophenyl) acetonitrile under basic conditions and proceeds with concomitant cyclisation. This sequence offers a one-pot synthesis of new fluorescent heterocyclic compounds, 8-chloro-3-alkyl-3H-imidazo[4,5-a]acridine-11-carbonitriles. The fluorescence of all compounds was intense and fluorescence quantum yields were very high (>0.85) for all of them.

The synthesis of a new series of 8-bromo-6-alkyl-1-aryl-6H-isoxazolo[4,3-e]indole derivatives is described. All the newly synthesized compounds were screened for their antibacterial activity against Escherichia coli HB101, Staphylococcus aureus pathogens (methicillin resistant S. aureus and methicillin susceptible S. aureus), Pseudomonas aeruginosa, and Bacillus subtilis; also MIC values of these compounds were determined.

Silica gel-supported polyphosphoric acid (PPA-SiO2) was found to be highly efficient, eco-friendly and recyclable heterogeneous catalyst for the synthesis of 2,4,6-triarylpyridines through one-pot three-component reaction of acetophenone, aryl aldehydes, and ammonium acetate under solvent-free conditions. This method has several advantages, such as simple procedure with an easy work-up, short reaction times, and high yields. Furthermore, the catalyst could be recycled after a simple work-up, and used at least three times without substantial reduction in its catalytic activity.

The synthesis of a new series of 8-bromo-6-alkyl-1-aryl-6H-isoxazolo[4,3-e]indole derivatives is described. All the newly synthesized compounds were screened for their antibacterial activity against Escherichia coli HB101, Staphylococcuse aureus pathogens (methicillin resistant S. aureus and methicillin susceptible S. aureus), Pseudomonas aeruginosa, and Bacillus subtilis; also MIC values of these compounds were determined.