Supramolecular Self-Assembly of Porphyrin and Metallosurfactant as a Drug Nanocontainer Design

The combined method of treating malignant neoplasms using photodynamic therapy and chemotherapy is undoubtedly a promising and highly effective treatment method. The development and establishment of photodynamic cancer therapy is closely related to the creation of sensitizers based on porphyrins. The present study is devoted to the investigation of the spectroscopic, aggregation, and solubilization properties of the supramolecular system based on 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TSPP) and lanthanum-containing surfactant (LaSurf) in an aqueous medium. The latter is a complex of lanthanum nitrate and two cationic amphiphilic molecules of 4-aza-1-hexadecylazoniabicyclo[2.2.2]octane bromide. The mixed TSPP–LaSurf complexes can spontaneously assemble into various nanostructures capable of binding the anticancer drug cisplatin. Morphological behavior, stability, and ability to drug binding of nanostructures can be tailored by varying the molar ratio and the concentration of components. The guest binding is shown to be additional factor controlling structural rearrangements and properties of the supramolecular TSPP–LaSurf complexes.

Insights into the Aggregation Behaviour of a Benzoselenadiazole-Based Compound and Generation of White Light Emission

We have designed and synthesized the benzoselenadiazole (BDS) based donor-acceptor-donor (D-A-D) π-conjugated compound 4,7-di((E)styryl)benzo[2,1,3]selenadiazole (1). A single-crystal study of 1 shows J-type molecular aggregation in the solid state. The crystal packing of 1 shows head-to-head dimeric intermolecular assembly via Se⋅⋅⋅N interactions while staircase-type interlock molecular packing has occurred via Se⋅⋅⋅π interaction. The staircase-type interlock packing of dimeric molecular arrangement induces sheet-type, herringbone type architecture along crystallographic a axis and ab plane via CH⋅⋅⋅π interactions. Interestingly, the J-type aggregation of 1 in solid state changes to H-type aggregation upon UV-irradiation. Moreover, our spectroscopic findings in solution state reveal H-type of aggregation of 1 in 90 % aqueous THF. We have further demonstrated white light emission in the binary mixture of 1 and 1-pyrenemethanol (2) in 90 % aqueous THF. Our study reveals solvent specific co-assembly of H-aggregated 1 and 2 in 90 % aqueous THF solution, which shows white light emissive properties with the Commission Internationale de l'Eclairage (CIE) chromaticity coordinates (0.32, 0.31). The observed white light emission arises mainly due to the combination of red light from H-aggregated 1, blue light from monomeric 2 and green light from excimers of 2.

An amphiphilic manganese porphyrin-paired ionic copolymer: a highly efficient biphasic transfer catalyst for the selective oxidation of olefins with O2 and TBHP

A novel amphiphilic manganese porphyrin-paired ionic copolymer, {ADA-INA-[Mn(TPPS)(OAc)]}_n, was prepared by the self-assembly process of non-cross-linked amphiphilic polymeric ligands with inorganic species.

Effects of Substitution on Solid-State Fluorescence in 9-Aryl-9-methyl-9H-9-silafluorenes

Aromatic groups were incorporated into 9H-9-silafluorene units at the 9-position (mono-9H-silafluorenes) and 9,9'-positions (di-9H-9-silafluorenes). The aryl substituents showed weak conjugation to the 9H-9-silafluorene for 9-aryl substituted ones 1-7 and a 9,9'-phenylene substituted one (compound 8) and they exhibited similar absorption and emission spectra. The 9H-9-silafluorene 10 containing a 5,5'-(2,2'-bithiophenyl) group showed a significantly red-shifted absorption and fluorescence maxima in the solid-state. Single-crystal X-ray diffraction studies found J-type aggregated structures formed by intermolecular CH-π interactions (ca. 2.6-2.7 Å). Density functional theory (DFT), time-dependent DFT (TD-DFT), and configuration interaction single (CIS) calculations were conducted to explain the observed optical properties.

New insight into the photophysics and reactivity of trigonal and tetrahedral arylboron compounds

The photophysics and reactivity of two tetraphenylborate salts and triphenylborane have been studied using ultrafast transient absorption, steady-state fluorescence, electron paramagnetic resonance with spin trapping, and DFT calculations. The singlet excited state of tetraarylborates exhibit extended π-orbital coupling between two adjacent aryl groups. The maximum fluorescence band, as well as the transient absorption bands centered at 560 nm (τ = 1.05 ns) and 680 nm (τ = 4.35 ns) are influenced by solvent viscosity and polarity, indicative of a twisted intramolecular charge transfer (TICT) state. Orbital contour plots of the HOMO and LUMO orbitals of the tetraarylboron compounds support the existence of electron delocalization between two aryl groups in the LUMO. This TICT-state and aryl-aryl electron extension is not observed for the trigonal arylboron compound, in which excited π-orbital coupling only occurs between the boron atom and one aryl group, which restricts the twist motion of the aryl-boron bond. The excited triplet state is deactivated primarily through aryl-boron bond cleavage, yielding aryl and diphenylboryl radicals. In the presence of oxygen, this photochemistry results in phenoxyl and diphenylboroxyl radicals, as confirmed by EPR spectroscopy of spin trapped radical adducts. The TICT transition and radical generation is not expected for BoDIPY molecules where the rotational vibration of the B-aryl bond is rigid, restricting changes in the geometric structure. In this sense, this work contributes to the development of new BoDIPY derivatives where the TICT transition may be observed for aryl ligands with free rotational vibrations in the BoDIPY structure.

Phosphonate appended porphyrins as versatile chemosensors for selective detection of trinitrotoluene

Fluorescent molecular probes based on phosphonate-functionalized porphyrin derivatives have been designed for selective detection of nitroaromatics. It is shown that molecular recognition is based on cooperative hydrogen bonding and π-π stacking interactions with electron-deficient molecules (nitroaromatic compounds, NACs), displaying superior detection toward trinitrotoluene (TNT). The P═O functional groups decrease the lowest unoccupied molecular orbital (LUMO) energy level of the porphyrins and, consequently, facilitate the electron inoculation to TNT through a photoinduced electron transfer (PET) process. The hydroxyl groups of the phosphonates and pyrrole -NH protons are further engaged in donor-acceptor interactions with TNT by strong intermolecular hydrogen bonding interactions (as evidenced by single crystal X-ray, NMR, and density functional theory (DFT)) showing turn off fluorescence behavior. The nonplanarity of the porphyrins induced by protonation at the central core of the porphyrin H4TPPA(2+) undergoes additional interactions, furnishing an anomalous increase in the selectivity of TNT at nanomolar levels in solution (limit of detection, LOD ∼ 5 nM). Porphyrin-doped hybrid PMMA [poly(methyl methacrylate)] polymer films demonstrate the reversibility of the fluorescence behavior and exhibit high photostability. The formation of discrete molecular aggregates on the surface of hybrid films and efficient diffusion of TNT vapors (10 ppb) displayed high selectivity in the solid state. The hybrid films are further used to demonstrate the detection of NACs in the aqueous medium, ultimately providing a platform for a practical strategy and implementation for the detection of toxic NACs.