The increasing demand for sustainable energy solutions has strengthened the search for new materials in triboelectric nanogenerator (TENG) design to improve output and device performance. Although several materials have been studied, the triboelectric series remains limited to a few classes, including oxides, 2D materials, MOFs, and polymers. Developing efficient, low-cost electron donors offers new hope for improving TENG performance. Most studies focus on polymers or inorganic compounds, with limited exploration of organic molecules with strong electron-donating or acceptor properties. The present manuscript focuses on phenothiazine (PTZ) and its derivative, N-ethyl-phenothiazine (NEt-PTZ), as a new class of triboelectric positive material for the TENGs. Utilizing their conjugated aromatic frameworks and the electron-donating nature of nitrogen and sulfur heteroatoms to improve charge transfer. A one-step synthesis process for NEt-PTZ demonstrated superior triboelectric performance compared to PTZ, producing an output of 450 V and 80 & micro;A, owing to its enhanced electron-donating properties. The device successfully powered wristwatches, calculators, and up to 400 LEDs, and exhibited stable operation over 10 000 mechanical cycles. This research not only broadens the triboelectric material library but also introduces a new category of dye-based electron-donating materials, offering a scalable and straightforward method to improve energy harvesting and self-powered device applications.

Artificial photosynthetic donor-acceptor (D-A) systems display photo-induced energy (PEnT) and electron transfer (PET) processes as operating mechanisms, through which the photo-excited donor is decayed to the ground state by transferring, either the excited state energy or electron, to the acceptor, eventually leading to the formation of excited acceptor or charge-separated state, respectively. Compared to PET, PEnT is considered as a non-invasive pathway as it does not generate any radical ion-pairs, even for a transient period, which is quite desirable for biological applications. Although great efforts are made, it is still of utmost importance to develop PEnT operating D-A systems that can convert high-energy UV-light to visible light efficiently. Here in, we report mono- and di-benzothiazole appended borondipyrromethenes, BTZ-BODIPY and DiBTZ-BODIPY, in which the benzothiazole behaves as the energy transferring antenna and BODIPY as the receiver. As meso-substitution of the BODIPY yields molecular rotamers and leads to the loss of excited-state energy, a strategic synthetic methodology is adopted to attach one or two BTZ moieties to the pyrrole skeleton of the BODIPY platform via ester linkage(s), and the PEnT from 1BTZ* to BODIPY, in solvents of varied polarity, was explored. Optical absorption studies displayed marginal interactions between the chromophores and, more importantly, showed the scope of selective photo-excitation of the BTZ or BODIPY moieties in the dyad and triad. Electrochemical studies involving both the dyad and triad revealed that the first oxidation and reduction processes are associated to the BODIPY fragment, which corroborated-well with the results obtained from frontier molecular orbital calculations. Interestingly, in case of BTZ-BODIPY and DiBTZ-BODIPY, steady-state fluorescence studies involving the photo-excitation of the BTZ moiety revealed quenching of the BTZ emission with simultaneous appearance of the BODIPY emission indicating the occurrence of the PEnT from 1BTZ* to BODIPY leading to the formation of BTZ-1BODIPY*. The driving forces of the energy transfer were evaluated to be exothermic in all the solvents signifying the importance of BTZ as the energy donor and BODIPY as the energy acceptor in the PEnT based D-A systems.

Panchromatic azaborondipyrromethenes, 1, 2, and 3, containing phenoxazine (PHO) and naphthalene tethered at 1,7 and/or 3,5-positions of the azaBODIPY platform were synthesized and photo-induced energy (PEnT) and electron transfer (PET) events were investigated. Optical absorption spectra have displayed broad absorption, from 250 to 1000 nm, in 1 and 2. Parallel electrochemical and computational studies revealed that PHO moiety in 1 and 2 was easier to oxidize compared to azaBODIPY suggesting that PHO moiety would behave as an electron donor and azaBODIPY as electron acceptor in PET reactions in these compounds. Steady-state fluorescence studies have revealed that, upon excitation of PHO moiety in 1 and 2, the emission of PHO and azaBODIPY moieties were quenched indicating the occurrence of PET from the singlet excited phenoxazine to the azaBODIPY. In contrast, excitation of naphthalene moiety in 3 revealed the quenched emission of naphthalene with concomitant appearance of the azaBODIPY emission suggesting the occurence of PEnT from (1)naphthalene* to the azaBODIPY. Fascinatingly, in 1, excitation of naphthalene moiety yielded quenched emissions of naphthalene and azaBODIPY moieties indicating the occurence of sequential PEnT from (1)(naphthalene)* to azaBODIPY followed by the PET from PHO to (1)(azaBODIPY)* leading to the formation of a charge-separated state (PHO)(2)(+center dot)-azaBODIPY(center dot)-(Naph)(2). Fluorescence decay studies revealed that the PEnT and PET in these compounds occur with rate constants of similar to 10(9) s(-1) - 10(10) s(-1).

A series of benzothiazole (BTZ) functionalized corrole (Cor) based donor-acceptor systems, Dyad-1, Dyad-2, and Dyad-3, with varied spacers, namely phenyl, biphenyl, and ethoxyphenyl respectively, were synthesized and the photoinduced energy transfer (PEnT) and electron transfer (PET) events were explored. Optical absorption studies have revealed negligible ground-state electronic interactions between the two chromophores. Steady-state fluorescence studies performed by selectively exciting the BTZ unit at 305 nm revealed a pronounced quenching of the BTZ emission, accompanied by the emergence of the corrole fluorescence indicating the occurrence of the PEnT from 1BTZ* to corrole. However, when the corrole moiety of dyads is excited at 410 nm, the emission is not quenched and found comparable with the emission intensity of the control compound, Ph-Cor, indicating that PEnT is the major photophysical pathway responsible for the quenching of BTZ emission. The electrochemical studies have shown that the first oxidation and reduction are results of the corrole moiety, corroborating with the computational results, implying that the occurrence of the PET is minimal in these dyads. Parallel lifetime measurements of the dyads have displayed a bi-exponential decay for the BTZ emission, but an unquenched corrole excited state, supporting the occurrence of the PEnT in these dyads.

Panchromatic dyes extending the absorption up to the near-infrared region stand out as excellent candidates for light harvesting and biological applications. One of the viable ways to construct panchromatic dyes involves the strategic selection of a molecular platform that can accommodate multiple chromophores absorbing at varied wavelength ranges. Even though azadipyrromethene (azaBODIPY) offers such a molecular skeleton, reports on broadband absorbing azaBODIPYs and related photoinduced interchromophore energy/electron transfer events intending to provide desirable functions such as electron migration and charge separation (CS) are still inadequate. In this context, multiheteroaromatic tethered azaBODIPY, (PTZ)2-AB-(TPA)2, containing phenothiazine (PTZ) and triphenylamine (TPA) integrated into azaBODIPY core has been synthesized and light-induced electron transfer events were explored. Parallely, control compounds involving azaBODIPYs with either TPA or PTZ moieties, (Ph)2-AB-(TPA)2 and (PTZ)2-AB-(Ph)2, and pristine Et-PTZ and TPA were synthesized, and the roles of the individual constituents in the photoinduced events are investigated. Optical absorption studies have revealed that the substitution of azaBODIPY skeleton with PTZ and TPA moieties at 1,7- and 3,5-positions enhanced the extended π-conjugation and resulted in broader absorption extending beyond 1000 nm. Electrochemical studies have displayed first oxidation from either TPA or PTZ, and first reduction from the azaBODIPY moieties indicating that TPA or PTZ would behave as electron donors and azaBODIPY as the electron acceptor, and computational studies have corroborated the results. Steady-state fluorescence studies in solvents of varied polarity, involving selective excitation of PTZ at 265 nm and TPA at 300 nm resulted in quenching of the PTZ or TPA emission indicating the occurrence of photoinduced electron transfer (PET) from 1PTZ* or 1TPA* to azaBODIPY. Time-correlated single photon counting studies confirmed the quenching of overall lifetimes of the azaBODIPYs indicating the presence of PET within these systems. Systematic femtosecond transient absorption studies revealed the optical signatures of TPA+• or PTZ+• displayed at 550 and 650 nm, respectively, authenticating the occurrence of PET from excited TPA or PTZ to azaBODIPY with a very short formation time of CS states (14, 61, and 7 ps for (PTZ)2-AB-(Ph)2, (Ph)2-AB-(TPA)2 and (PTZ)2-AB-(TPA)2, respectively), and a long charge recombination in the nanosecond time domain, and highlighted the versatility of azaBODIPY as an electron relay in light-induced events.

Near-infrared absorbing azaborondipyrromethenes (azaBODIPYs), 1, 2, and 3, tethered with phenothiazine (PTZ) and/or naphthalene at 1,7 and/or 3,5 positions, were synthesized and photoinduced energy (PEnT) and electron (PET) events occurring within these compounds were systematically studied. Steady-state fluorescence studies have shown that, when the phenothiazine moiety, in 1 and 2, was selectively excited, the fluorescence of the PTZ and azaBODIPY was quenched, indicating the occurrence of PET from the singlet excited phenothiazine to the azaBODIPY. On the other hand, when the naphthalene moiety in 3 was excited, the emission of the naphthalene was observed to be quenched with the concomitant appearance of the azaBODIPY emission indicating the display of PEnT from (1)naphthalene* to the azaBODIPY. Interestingly, in the case of 1, selective excitation of naphthalene resulted in the quenching of both the naphthalene and azaBODIPY emissions, indicating the possibility of PEnT from (1)naphthalene* to azaBODIPY followed by a tandem PET from the ground state of the phenothiazine moiety to the azaBODIPY. The present work showed the synthetic scope of introducing two different chromophores onto the azaBODIPY platform to produce panchromatic dyes and systematically revealed the significance of the individual constituents, PTZ and naphthalene as electron and energy donors, and azaBODIPY as an excited state energy or electron receiver in the PET and PEnT processes.

Photo-induced energy transfer (PEnT) is a non-invasive photophysical phenomenon by which an excited state energy donor decays to the ground state by transferring the energy to the acceptor, without generating any radical ion-pairs, which is quite desirable for designing molecular probes for biological applications. For the first time, a water soluble benzothiazole (BTZ)-borondipyrromethene (BODIPY) dyad, BTZ-BODIPY-DA, displaying PEnT was synthesized, and used for detecting Aβ40 fibrils. Steady-state and time-resolved fluorescence studies in polar organic solvents and also in PBS, involving the photoexcitation of the BTZ moiety of the dyad, revealed the occurrence of PEnT from 1BTZ* to BODIPY. Upon binding with amyloid Aβ40 fibrils, a two-fold enhancement in the fluorescence intensity and enhanced 1BODIPY* lifetime was observed. Binding of the dyad with Aβ40 peptide and fibrils was explained using molecular dynamics simulations, which further supported that structural rigidification of the bound dyad is responsible for enhanced PEnT. Furthermore, the impact of amyloid binding on the kinetics of PEnT in the dyad was investigated using femtosecond transient absorption studies, and energy transfer rate, kEnT, of ∼1012 s-1 in the amyloid-bound dyad was measured, highlighting the potential use of the dyad as a non-intrusive PEnT operating fluorescent probe for detecting amyloid fibrils.

A photosynthetic antenna-reaction center model, BBA-PFCor comprised of N,N'-bis( biphenyl-4- yl) aniline (BBA) covalently functionalized to bis(pentafluoro)corrole moiety has been prepared and the contribution of the BBA as the photoinduced energy transfer antenna was investigated. UV-visible studies have shown that integrating the electron-rich BBA chromophore into the corrole core has broadened the soret band of the corrole moiety with the absorption spanning from 300 to 700 nm. Electrochemical studies, in corroboration with the computational calculations, revealed that, BBA moiety can act as an electron reservoir and, in the excited state, it would transfer the excited energy to the corrole moiety in the dyad. Steady-state fluorescence studies have demonstrated that, upon photoexcitation of the BBA moiety of BBA-PFCor at 310nm in solvents of varied polarity, the BBA emission centered at 400 nm was observed to be quenched, with the concomitant appearance of the corrole emission from 500 to 700 nm, indicating the happening of photoinduced energy transfer (PEnT) from (1)BBA* to corrole moiety. Parallel control experiments involving the excitation of the corrole moiety at 410 nm did not result in the diminishing of the corrole emission, suggesting that the quenching of the BBA emission in BBA-PFCor is majorly due to intramolecular PEnT from (1)BBA* to corrole moiety leading to the formation of singlet excited corrole, that is, (1)BBA*-PFCor -> BBA(-1)PFCor*. The free energy changes of PEnT, Delta G(EnT), were found to be thermodynamically feasible in all the solvents used for the study. Parallel time-resolved fluorescence studies were congruent with the steady-state fluorescence results and provided further evidence for the occurrence of ultrafast PEnT from (1)BBA* -> corrole in the dyad with the rates of energy transfer (k(EnT)) of similar to 10(8) s(-1).

Panchromatic azaborondipyrromethenes directly connected with N,N-ditolylaniline (TPA) and naphthalene (Naph) at 1,7- and/or 3,5-positions of the azaBODIPY platform, 1, 2, and 3, were synthesized and the roles of the individual chromophore constituents in the photo-induced energy and electron transfer processes have been investigated. Optical absorption studies have indicated that integrating the complementary absorbers, naphthalene and TPA moieties, into the azaBODIPY core yielded broad-band capturing dyes with the absorption ranging from 250-1000 nm. Parallel electrochemical studies revealed that TPA moiety in 1 and 2 is easier to oxidize when compared to azaBODIPY moiety, which are in congruent with the computational studies indicating that TPA moiety would behave as an electron donor and azaBODIPY as an acceptor in PET processes. Steady-state fluorescence studies indicated that the photo-excitation of the TPA moiety in 2 resulted in the occurrence of PET from 1 TPA* to azaBODIPY generating (TPA)2 + ⋅-(azaBODIPY)- ⋅ while that of naphthalene in 3 resulted in PEnT from 1 (naphthalene)* to azaBODIPY forming (Naph)2 -1 (azaBODIPY)*. Interestingly, in 1, excitation of naphthalene moiety resulted in sequential PEnT from 1 (naphthalene)* to azaBODIPY followed by the PET from TPA to 1 (azaBODIPY)* generating a charge-separated state, (TPA)2 + ⋅-(azaBODIPY)- ⋅-(Naph)2 Fluorescence lifetime studies have indicated that the electron and energy transfer processes occurred in nanosecond time scales.

A dual-dye integrated polyaromatic azaborondipyrromethene was synthesized and its role as an electron and energy relay in photoinduced process was investigated.

A series of phenothiazine-C60/70 dyads containing fulleropyrrolidine tethered to C-3 position (C60-PTZ and C70-PTZ) or to the heteroatom N-position via either phenyl (C60-Ph–PTZ and C70-Ph-PTZ) or phenoxyethyl linkers (C60-PhOEt-PTZ and C70-PhOEt-PTZ) of the phenothiazine were synthesized and light-induced electron transfer events were explored. Optimized studies suggested that the highest molecular orbital (HOMO) resides on donor phenothiazine moiety while lowest molecular orbital (LUMO) on the acceptor fulleropyrrolidine moiety of the dyads. Optical and electrochemical properties suggested no electronic communication between the donor and acceptor moieties in the ground state. However, steady-state emission studies in solvents of varied polarity, involving selective excitation of C60/C70, disclosed that the emission intensity of C60/C70 was quenched in the dyads in the increasing order, C60/70-PTZ > C60/70-Ph-PTZ > C60/70-PhOEt-PTZ as a consequence of the donor–acceptor distance resulted due to spacer lengths. Also, the emission quenching is more pronounced in polar solvents such as DMF compared to a non-polar solvent, toluene. With the support of parallel electrochemical studies, the emission quenching is attributed to intramolecular photo-induced electron transfer occurring from PTZ to (C60/C70)* generating a radical ion pair, PTZ+⋅–C60−⋅/PTZ+⋅–C70−⋅. Finally, bulk heterojunction (BHJ) solar cells devices inverted fashion prepared by employing the dyads as acceptors, and PTB7 as donor, suggested that the devices prepared from C70 derivatives i.e., PTB7:C70-PTZ and PTB7:C70-PhOEt-PTZ exhibited better power conversion efficiency of 2.66

[Formula: see text]-bis (4′-tert-butylbiphenyl-4-yl)aniline) tethered zinc porphyrins, (BBA) 4 - ZnP, (BBA- Ph) 4 - ZnP, and (BBA- OEtOPh) 4 - ZnP with varied spacer distances have been synthesized and photosynthetic antenna-reaction center models were constructed via axial co-ordination with fulleropyrrolidines, C 60 Im and C 70 Im. Selective excitation of the BBA moiety in the porphyrins at 355 nm resulted in the quenching of the emission intensity of the BBA followed by the concomitant appearance of the ZnP emission at 600–640 nm indicating the occurrence of the photoinduced energy transfer from 1 BBA * to ZnP. When the zinc porphyrins are titrated with C 60 Im and C 70 Im, supramolecular complexes of the type, (BBA) 4 -ZnP:[Formula: see text]Im/[Formula: see text]Im are formed and the complex formation was monitored by UV-visible spectroscopic studies. Steady-state fluorescence studies involving the excitation of the ZnP at 550 nm displayed the diminished fluorescence intensity of the ZnP emission indicating the photoinduced electron transfer from 1 ZnP * to fullerenes. More interestingly, when the BBA moiety is excited in the supramolecular complexes, the emission of both the BBA and ZnP were decreased gradually indicating the occurrence of PEnT from 1 BBA * to ZnP followed by a sequential electron transfer from 1 ZnP * to C 60 Im or C 70 Im indicating the formation of a charge-separated state in these complexes.

Many fixed-dose combinations (FDCs) have recently been used as a potential therapy for patients with hypercholesterolemia and a high risk of cardiovascular disease. In the present study, bempedoic acid and ezetimibe have been simultaneously determined in rat plasma through developing a simple, accurate, precise and rapid HPLC–PDA method. The effective chromatographic separation was performed using an X-bridge C18 (150 × 4.6 mm, 3.5 µm) with mobile phase comprised of 0.1% TEA in water (pH was adjusted to 2.5 with formic acid) and acetonitrile (40:60, v/v) and was eluted at a flow rate 1 mL min−1 using an isocratic elution mode at 236 nm as detection wavelength. The calibration curves for plasma samples showed linear relationships for bempedoic acid and ezetimibe and the concentrations were found to be in the range of 1.8–36.0 ng mL−1, 0.1–2.0 ng mL−1 with correlation coefficients (r2) of 0.9997 and 0.9996, respectively. Limits of detection (LOD) and limits of quantification (LOQ) are determined to be 0.6 ng mL−1, 1.8 ng mL−1 for bempedoic acid and 0.03 ng mL−1, 0.1 ng mL−1 for ezetimibe in plasma samples, respectively. Recovery studies of bempedoic acid and ezetimibe were obtained in the range of 94.2–98.4% and 94.4–98.8%, respectively.

Background A precise, simple, accurate, and quick HPLC–PDA method for the determination of eluxadoline and rifaximin in rat plasma was developed and validated in this study. In this method, Loperamide hydrochloride was used as the internal standard and plasma samples were prepared using a liquid–liquid extraction technique for which acetonitrile was a solvent. An Agilent Symmetry C8 column (5 µm, 250 mm × 4.6 mm) at 283 nm and isocratic elution using HPLC grade acetonitrile and 7 mM TEA (pH 2.5) with a ratio of (40: 60 v/v) was used as a mobile phase and the flow rate employed was 1 mL min −1 . A satisfactory chromatographic separation was accomplished. Results An HPLC–PDA method for the determination of eluxadoline and rifaximin with retention times of 3.06 and 7.82 min, respectively, was developed. The calibration curves appear linear for both eluxadoline and rifaximin in the range of 5–200 ng mL −1 and 10–400 ng mL −1 , and the corresponding correlation coefficient values were found to be 0.9999 and 0.9998 respectively. Lower limits of quantification (LLOQ) for eluxadoline and rifaximin were evaluated to be 5.0 ng mL −1 and 10.0 ng mL −1 , respectively. The accuracy and precision results in all validation experiments were within the acceptance limits of FDA guidelines. Conclusion The developed HPLC–PDA approach was fully validated to meet the USFDA guidelines for bioanalytical method validation in terms of precision, accuracy, and stability. The presented approach could be beneficial for the determination of ELX and RFX in rat plasma, according to validation parameters. This is one of the efficient method to study the pharmacokinetics of ELX and RFX in rats. Graphical abstract

Free base porphyrin hosts, m-(PTZ)4-H2P and p-(PTZ)4-H2P, tethered with four phenothiazine moieties at the meso-position via a flexible ethoxy phenyl linker were synthesized and used for the selective complexation of fullerenes, C60 and C70.

Molecularly imprinted polymers (MIPs) belong to the illustrious examples of bio-mimicking recognizing materials.1 They have found numerous applications in the fabrication of selective chemosensors.2 Their analytical parameters, such as sensitivity, selectivity, and detectability, are almost as high as those of biosensors. Additionally, MIP based chemosensors are superior to biosensors concerning their ease of fabrication, durability, and tolerance to harsh conditions, including elevated or decreased temperature, high ionic strength, extreme pH values, the presence of heavy metal ions and organic solvents in the samples. Conductive MIPs have recently become more frequently applied. That is mainly due to the easy control of MIPs deposition as thin films by electropolymerization.3 For the electrochemical determination of non-electroactive analytes, some external redox probe is usually added to the test solution. It is assumed that target analyte molecules' binding into molecular cavities causes MIP film swelling or shrinking. According to the so-called "gate effect" mechanism, this polymer "breathing" causes changes in the redox probe permeability through an MIP film, thus changing faradaic current corresponding to the redox probe's reduction or oxidation in cyclic voltammetry (CV) and differential pulse voltammetry (DPV) determinations.4-5 This mechanism is operative for nonconductive MIP films. Another mechanism may be considered for surface imprinted macromolecular compounds, e.g., proteins. A drop in the faradaic current of the redox probe accompanying protein adsorption originates from physical blocking of the electrode surface by their bulky nonconductive molecules.6 But both of these mechanisms seem to be invalid in case of electrochemical sensors based on conductive MIP films. In our previous studies, we demonstrated that a drop in the DPV current, caused by the appearance in a solution of an analyte, at conductive MIP film-coated electrodes might originate not from hindering the diffusion of the redox probe through the film but from changes in electrochemical properties of the film itself 7. Suppose the redox probe diffusion through the MIP film is not a decisive parameter for the faradaic current involving. Then, in the, e.g., DPV, determinations of electroinactive analytes at conductive MIP film-coated electrodes, this diffusion may be eliminated. For that the redox probe could be immobilized inside the MIP film matrix. Herein, we propose to deposit a self-reporting MIP film and apply it for fabrication of the selective electrochemical sensor determining the target analyte in the redox probe free test solutions. For that purpose, a ferrocene redox probe was covalently immobilized in a bis-bithiophene polymer molecularly imprinted with the p-synephrine template. Simultaneously, this polymer was deposited on the Pt electrode as a thin film. After the template extraction from the film, the analyte was determined with differential pulse voltammetry (DPV) in a redox probe free solution. That was possible because the internal ferrocene redox probe generated the DPV analytical signal. The thickness and morphology of the film were crucial for the sensor's performance. The mechanism of this redox self-reporting MIP film-based chemosensor was examined with electrochemical methods, simultaneous piezomicrogravimetry and electrochemistry at an electrochemical quartz crystal microbalance, and surface plasmon resonance spectroscopy. The devised chemosensor was applied for selective p-synephrine determination in a concentration range of 2.0 to 75 nM. References Cieplak, M.; Kutner, W., Artificial biosensors: How can molecular imprinting mimic biorecognition? Trends Biotechnol. 2016, 34 (11), 922-941. Uzun, L.; Turner, A. P. F., Molecularly-imprinted polymer sensors: realising their potential. Biosens. Bioelectron. 2016, 76, 131-144. Huynh, T.-P.; Sharma, P. S.; Sosnowska, M.; D'Souza, F.; Kutner, W., Functionalized polythiophenes: Recognition materials for chemosensors and biosensors of superior sensitivity, selectivity, and detectability. Prog. Polym. Sci. 2015, 47, 1-25. Yoshimi, Y.; Narimatsu, A.; Nakayama, K.; Sekine, S.; Hattori, K.; Sakai, K., Development of an enzyme-free glucose sensor using the gate effect of a molecularly imprinted polymer. J. Artif. Organs 2009, 12 (4), 264-270. Sharma, P. S.; Garcia-Cruz, A.; Cieplak, M.; Noworyta, K. R.; Kutner, W., 'Gate effect' in molecularly imprinted polymers: the current state of understanding. Curr. Opin. Electroche. 2019, 16, 50-56. Moreira, F. T. C.; Dutra, R. A. F.; Noronha, J. P. C.; Fernandes, J. C. S.; Sales, M. G. F., Novel biosensing device for point-of-care applications with plastic antibodies grown on Au-screen printed electrodes. Sens. Actuators, B 2013, 182, 733-740. Lach, P.; Cieplak, M.; Majewska, M.; Noworyta, K. R.; Sharma, P. S.; Kutner, W., "Gate Effect" in p-Synephrine Electrochemical Sensing with a Molecularly Imprinted Polymer and Redox Probes. Anal. Chem. 2019, 91 (12), 7546-7553. Figure 1

Benzothiazole (BTZ)-zinc porphyrin (ZnP) dyads, Dyad-1 and Dyad-2 connected together with two different spacers, ester and ethoxy esters, were synthesized and light induced energy and electron transfer events were investigated. Within these dyads, due to the spectral overlap of the BTZ emission with the ZnP absorption, a selective photoexcitation of BTZ at 325 nm resulted in the photo-induced energy transfer (PEnT) from 1BTZ* to ZnP displaying the quenching of the BTZ emission followed by the concurrent appearance of the ZnP emission at 600 and 650 nm suggesting the formation of the 1ZnP* [Formula: see text]. 1BTZ*-ZnP [Formula: see text] BTZ-1ZnP*. When the dyads are titrated with imidazole appended fullero[C[Formula: see text]/C[Formula: see text]]pyrrolidines, four supramolecular triads, involving the axial co-ordination of the imidazole to the zinc center of the ZnP, were formed and the assembly formation was systematically monitored by the optical absorption technique. Cyclic voltammetry and the density functional theory calculations have revealed that, in these triads, the zinc porphyrin acts as an electron donor and fullerene moiety as the electron acceptor. Steady state fluorescence studies revealed that, upon selective excitation of the ZnP moiety at 550 nm, the emission of ZnP at 600 and 650 nm was quenched revealing the occurrence of photo-induced electron transfer (PET) from 1ZnP* to fullerene moiety leading to the formation of charge separated state [Formula: see text]. BTZ-1ZnP* : (ImC[Formula: see text] BTZ-ZnP[Formula: see text]:(ImC[Formula: see text]. More importantly, when the supramolecular triads were excited at 325 nm, the wavelength at which the BTZ absorbs predominantly, the emission of the BTZ moiety which was quenched due to PEnT from 1BTZ* to ZnP followed by the PET from 1ZnP* to fullerene indicates the probability of occurrence of 1BTZ*-ZnP:(ImC[Formula: see text] [Formula: see text] BTZ-1ZnP*[Formula: see text]: (ImC[Formula: see text] BTZ-ZnP[Formula: see text]:(ImC[Formula: see text].

The synthesis, characterization, and electrochemical and photophysical properties of the phosphonate-derivatized carbazole (CBZ) and boron dipyrromethene (BODIPY) chromophores in the dyes, BODIPY(CBZ)2PO3H2 (8) and BODIPY(Tol)2PO3H2 (7), are described. The oxide-bound dyes have been explored as light absorbers in dye-sensitized photoelectrosynthesis cell (DSPEC) applications. The BODIPY-CBZ phosphonate ester (6) features a broad, intense UV-visible absorption spectrum with absorptions at 297 and 650 nm that arise from mixed transitions at the CBZ and BODIPY units. Electrochemical measurements on BODIPY(CBZ)2Br (4) in 0.1 M [nBu4N][PF6] in dichloromethane, vs normal hydrogen electrode (NHE), reveal reversible oxidations at 1.19 and 1.41 V and a reversible reduction at -0.59 V. On indium tin oxide (ITO) and TiO2, a reversible one-electron oxidation appears for 7 at 0.86 and 0.90 V vs NHE in dichloromethane, respectively, which demonstrates the redox stability on metal oxide surfaces. The results of nanosecond transient absorption measurements on SnO2/TiO2 electrodes provide direct evidence for excited-state electron injection into the conduction band of TiO2 following 590 nm excitation. A longer lifetime for 8+ compared to 7+ is consistent with extensive intramolecular charge separation between the CBZ and BODIPY units on the surface. Photoelectrochemical studies on 8 on a SnO2/TiO2 photoanode resulted in sustained photocurrents with current maxima of ∼200 μA/cm2 with hydroquinone added as a reductant under 1 sun (AM1.5 100 mW·cm-2) illumination at pH 4.5 in 0.1 M acetate buffer and 0.4 M LiClO4. On mixed SnO2/TiO2 electrode surfaces, with the added catalyst [Ru(Mebimpy)((4,4'-(OH)2PO-CH2)2bpy)(OH2)]2+ and chromophores 7 and 8, addition of 0.1 M benzyl alcohol resulted in sustained photocurrents of 12 and 35 μA/cm2, consistent with oxidation to benzaldehyde.

Limited synthetic steps via low-cost starting materials are needed to develop large-scale light-active materials for efficient solar cells. Here, novel bis(4[Formula: see text]-tert-butylbiphenyl-4-yl)aniline (BBA) based A 3 B zinc porphyrin (GB) is synthesized and applied as a light harvesting/electron injection material in dye-sensitized solar cells. The GB sensitizer was characterized by various spectroscopic techniques and the optimized device shows [Formula: see text] of 10.98 ± 0.37 mA/cm 2 and power conversion efficiency (PCE) of 3.34 ± 0.26%. In addition, performance is enhanced up to ∼3.9% by the addition of co-adsorbent 3a,7a-dihydroxy-5b-cholic acid (chenodeoxycholic acid, CDCA) to minimize [Formula: see text]-[Formula: see text] staking of the planar porphyrin macrocycles. These results demonstrate that novel broad-absorbing light-active material (GB) could be used for indoor solar panels.

A panchromatic triad, consisting of benzothiazole (BTZ) and BF2-chelated boron-dipyrromethene (BODIPY) moieties covalently linked to a zinc porphyrin (ZnP) core, has been synthesized and systematically characterized by using H-1 NMR spectroscopy, ESI-MS, UV-visible, steady-state fluorescence, electrochemical, and femtosecond transient absorption techniques. The absorption band of the triad, BTZ-BODIPY-ZnP, and dyads, BTZ-BODIPY and BODIPY-ZnP, along with the reference compounds BTZ-OMe, BODIPY-OMe, and ZnP-OMe exhibited characteristic bands corresponding to individual chromophores. Electrochemical measurements on BTZ-BODIPY-ZnP exhibited redox behavior similar to that of the reference compounds. Upon selective excitation of BTZ (approximate to 290 nm) in the BTZ-BODIPY-ZnP triad, the fluorescence of the BTZ moiety is quenched, due to photoinduced energy transfer (PEnT) from (1)BTZ* to the BODIPY moiety, followed by quenching of the BODIPY emission due to sequential PEnT from the (BODIPY)-B-1* moiety to ZnP, resulting in the appearance of the ZnP emission, indicating the occurrence of a two-step singlet-singlet energy transfer. Further, a supramolecular tetrad, BTZ-BODIPY-ZnP:ImC(60), was formed by axially coordinating the triad with imidazole-appended fulleropyrrolidine (ImC(60)), and parallel steady-state measurements displayed the diminished emission of ZnP, which clearly indicated the occurrence of photoinduced electron transfer (PET) from (ZnP)-Zn-1* to ImC(60). Finally, femtosecond transient absorption spectral studies provided evidence for the sequential occurrence of PEnT and PET events, namely, (1)BTZ*-BODIPY-ZnP:ImC(60)-> BTZ-(BODIPY)-B-1*-ZnP:ImC(60)-> BTZ-BODIPY-(ZnP)-Zn-1*:ImC(60)-> BTZ-BODIPY-ZnP.+:ImC(60)(.-) in the supramolecular tetrad. The evaluated rate of energy transfer, k(EnT), was found to be 3-5x10(10) s(-1), which was slightly faster than that observed in the case of BODIPY-ZnP and BTZ-BODIPY-ZnP, lacking the coordinated ImC(60). The rate constants for charge separation and recombination, k(CS) and k(CR), respectively, calculated by monitoring the rise and decay of C-60(.-) were found to be 5.5x10(10) and 4.4x10(8) s(-1), respectively, for the BODIPY-ZnP:ImC(60) triad, and 3.1x10(10) and 4.9x10(8) s(-1), respectively, for the BTZ-BODIPY-ZnP:ImC(60) tetrad. Initial excitation of the tetrad, promoting two-step energy transfer and a final electron-transfer event, has been successfully demonstrated in the present study.