Boron-containing organic compounds are reported to have excellent luminescent properties, however, their ability to photosensitize singlet oxygen generation remains unexplored. The synthesis of several Schiff-base based boranils is reported, starting from commercially available salicylaldehydes and anilines. The iodo-functionalized derivatives were observed to aid in the photosensitized generation of singlet oxygen. Poly(methylmethacrylate) films incorporating these molecules were prepared and were demonstrated to be capable of serving as a reusable heterogeneous medium for the photosensitized degradation of organic water pollutants.

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The study of excited-state energy diffusion has had an important impact in the development and optimization of organic electronics. For instance, optimizing excited-state energy migration in the photoactive layer in an organic solar cell device has been shown to yield efficient solar energy conversion. Despite the crucial role that energy migration plays in molecular electronic device physics, there is still a great deal to be explored to establish how molecular orientation impacts energy diffusion mechanisms. In this work, we have synthesized a new library of solution-processable, Zn (alkoxycarbonyl)phenylporphyrins containing butyl (ZnTCB4PP), hexyl (ZnTCH4PP), 2-ethylhexyl (ZnTCEH4PP), and octyl (ZnTCO4PP) alkoxycarbonyl groups. We establish that, by varying the length of the peripheral alkyl chains on the metalloporphyrin macrocycle, preferential orientation and molecular self-assembly is observed in solution-processed thin films. The resultant arrangement of molecules consequently affects the electronic and photophysical characteristics of the metalloporphyrin thin films. The various molecular arrangements in the porphyrin thin films and their resultant impact were determined using UV-Vis absorption spectroscopy, steady-state and time-resolved fluorescence emission lifetimes, and X-ray diffraction in thin films. The films were doped with C60 quencher molecules and the change in fluorescence was measured to derive a relative quenching efficiency. Using emission decay, relative quenching efficiency, and dopant volume fraction as input, insights on exciton diffusion coefficient and exciton diffusion lengths were obtained from a Monte Carlo simulation. The octyl derivative (ZnTCO4PP) showed the strongest relative fluorescence quenching and, therefore, the highest exciton diffusion coefficient (5.29 × 10−3 cm2 s−1) and longest exciton diffusion length (~81 nm). The octyl derivative also showed the strongest out-of-plane stacking among the metalloporphyrins studied. This work demonstrates how molecular self-assembly can be used to modulate and direct exciton diffusion in solution-processable metalloporphyrin thin films engineered for optoelectronic and photonic applications.

The health hazards associated with heavy metal ions in water demand the development of efficient and portable sensors, for rapid onsite detection of these ions. Several research groups have developed colorimetric/visual sensors based on plasmonic nanomaterials and quantum dots (QDs). Attempts for specific detection of metal ions have been partially achieved through the interaction between the metal ion and the passivating ligands around the QD. However, the underlying mechanism is not clearly understood. Here, we have used water-soluble Mndoped ZnS QD to effectively detect Hg 2 + , Pb 2 + , and Cd 2 + through the quenching of QD emission and understand the mechanism of sensing. Stern-Volmer plots indicate that the quenching is static in nature for Pb 2 + , and Cd 2 + , while for Hg 2 + , it is a combination of static and dynamic quenching. Overall, the metal ions bind to the QD through the passivating ligand. After excitation, the electron from the conduction band of the QD can get injected to the metal ion -which decreases the photoluminescence of the QD. The electron injection depends on the reduction potential of the metal ion, the orbital overlap and the overall stabilization energy of the metal ions bound to the QD. Hence, this method of sensing is not selective to a specific metal ion. A solid state sensor of QD-rGO composite detects Pb 2 + down to 0.4 ppb. The findings will be important for future improvement of colorimetric/visual sensors based on QD emission.Heavy metal ions such as lead, mercury and cadmium pose severe potential threats to living beings as they can easily be accumulated in the body and cannot be detoxified by any chemical or biological processes. [1][2][3] Detections of these toxic metal ions are important and have received considerable interest. [4][5][6][7][8][9][10][11][12] Instrumental techniques such as inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectroscopy (AAS) are considered ideal methods to detect heavy metal ions at very low concentrations (∼ subppb). However, these methods suffer from disadvantages such as requirement of sophisticated instruments, time consump-tion, and high cost. Detecting heavy metal ions using rapid and easy methods with high sensitivity is a focal point of research.In the last two decades, there has been a significant development of several optical, [4][5][6][7] electrochemical, [8][9][10] and gel based sensors, [11,12] for sensing of heavy metal ions at trace levels (∼ 10 ppb). Sensors based on plasmonic nanomaterials show a change in color (shift in absorption wavelength) upon addition of the toxic heavy metal ions, depending upon the affinity of the heavy metal ion towards the surface capping agent on the nanoparticles. [13][14][15][16] These methods are restricted to solution state sensing and do not exhibit quick response. Therefore, there is an urge to develop visual sensors, which can effectively detect heavy metal ions rapidly (within seconds) under ambient conditions. [17] Due to their tunable and high photolumin...