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In this work, novel fluorophores with D–π–A architectures (ICz-1–ICz-6) were synthesized and investigated, where the indolo[3,2,1-jk]carbazole (ICz) framework is connected by an ethylene bridge with extensive donor moieties – e.g., fluorene, carbazole, phenothiazine, methoxyphenyl, bithiophene, and dibenzothiophene. The influences of the donor character of the substituents in the indolocarbazole derivatives on their thermal, optical and electrochemical properties were explored and compared with the quantum chemical calculations based on DFT and TD-DFT. All ICz-1–ICz-6 compounds emit blue light with emission peaks between 390 and 430 nm in solution, except for compound ICz-5 with a strong phenothiazine donor, which emits light at 463 nm. The ICz-6 derivative with the dibenzothiophene unit features an exception to Kasha's rule. For the selected compounds ICz-2, ICz-4, and ICz-5, preliminary electroluminescence tests were performed, both based on devices with a neat compound (ITO/PEDOT:PSS/ICz/Al) and with a guest–host configuration (ITO/PEDOT:PSS/PVK:PBD:ICz/Al), where two emission bands were detected covering the range from 400 to over 900 nm. Additionally, several multilayer OLED devices (ITO/PEDOT:PSS/poly-TPD/ICz-2–5/TPBi/LiF/Al) were prepared, and all diodes showed electroluminescence at 570 nm.

The ground- and excited-state properties of three novel complexes [ReCl(CO)3(Ln-κ2N)] bearing 2,2′:6′,2′′-terpyridine, 2,6-di(thiazol-2-yl)pyridine and 2,6-di(pyrazin-2-yl)pyridine functionalized with 9-carbazole attached to the central pyridine ring of the triimine core via phenylene linkage were investigated by spectroscopic and electrochemical methods and were simulated using density functional theory (DFT) and time-dependent DFT. To get a deeper and broader understanding of structure–property relationships, the designed Re(I) carbonyl complexes were compared with previously reported analogous systems – without any groups attached to the phenyl ring and bearing pyrrolidine instead of 9-carbazole. The results indicated that attachment of the N-carbazolyl substituent to the triimine core has less influence on the nature of the triplet excited state of [ReCl(CO)3(Ln-κ2N)] than the pyrrolidine group. Additionally, the impact of the ligand structural modifications on the light emission of the Re(I) complexes under external voltage was preliminarily examined with electroluminescence spectra of diodes containing the synthesized new molecules in an active layer.

We developed a method of aligning silver nanowires in a microchannel and fixing them to glass substrates via appropriate functionalization. The attachment of nanowires to the substrate is robust with no variation of their angles over minutes. Specific conjugation with photoactive proteins is observed using wide-field fluorescence imaging in real-time for highly concentrated protein solution, both in a microchannel and in a chip geometry. In the latter case we can detect the presence of the proteins in the dropcasted solution down to single proteins. The results point towards possible implementation of aligned silver nanowires as geometrically defined plasmonic fluorescence sensing platforms.

We observe correlation between the length of surface plasmon polariton propagation in silver nanowires and the enhancement of fluorescence intensity due to coupling with localized plasmon resonance...

Colloidal, oil-core polymer-shell nanocapsules (NCs), loaded with both upconversion NaYF4:Yb,Er nanoparticles (NPs) and CdSe quantum dots (QDs), were prepared via nanoemulsification/solvent-evaporation methods. Transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) techniques were used to comprehensively determine the structure, phase composition, and morphology of the NCs. Furthermore, we demonstrated that by simultaneously loading the hybrid fluorophores into the multimodal NCs, it is possible to combine their mechanistically distinct one- and two-photon luminescence properties. The two-photon absorption cross-section obtained at 850 nm for a single capsule was equal to 2.5 × 104 GM (Goeppert-Mayer units). Importantly, cytotoxicity studies indicated the potential of the co-encapsulated NPs and QDs for fluorescence imaging in biological specimens. We conclude that such non-toxic water-dispersible multifunctional nanohybrids represent a promising platform for advanced one- and two-photon induced fluorescence bioimaging and photonic sensing technologies.

We experimentally demonstrate that oriented assembly of red algal photosystem I (PSI) reaction centers on a plasmonically active Silver Island Film (SIF) leads to strong enhancement of both the fluorescence intensity and photocurrent generated upon illumination. PSI complexes were specifically attached to a monolayer of graphene deposited on the SIF layer. The results of comprehensive fluorescence microscopy point to the critical role of the SIF layer in enhancing the optical response of PSI, as we observe increased emission intensity. Hence, importantly, the strong increase of photocurrent generation demonstrated for the biohybrid electrodes can be directly associated with the plasmonic enhancement of the optical and electrochemical functionalities of PSI. The results also indicate that the graphene layer is not diminishing the influence of the plasmonic excitations in SIF on the absorption and emission of PSI. © The Royal Society of Chemistry 2020.

One of the crucial challenges for science is the development of alternative pollution-free and renewable energy sources. One of the most promising inexhaustible sources of energy is solar energy, and in this field, solar fuel cells employing naturally evolved solar energy converting biocomplexes—photosynthetic reaction centers, such as photosystem I—are of growing interest due to their highly efficient photo-powered operation, resulting in the production of chemical potential, enabling synthesis of simple fuels. However, application of the biomolecules in such a context is strongly limited by the progressing photobleaching thereof during illumination. In the current work, we investigated the excitation wavelength dependence of the photosystem I photodamage dynamics. Moreover, we aimed to correlate the PSI–LHCI photostability dependence on the excitation wavelength with significant (ca. 50-fold) plasmonic enhancement of fluorescence due to the utilization of planar metallic nanostructure as a substrate. Finally, we present a rational approach for the significant improvement in the photostability of PSI in anoxic conditions. We find that photobleaching rates for 5 min long blue excitation are reduced from nearly 100% to 20% and 70% for substrates of bare glass and plasmonically active substrate, respectively. Our results pave promising ways for optimization of the biomimetic solar fuel cells due to synergy of the plasmon-induced absorption enhancement together with improved photostability of the molecular machinery of the solar-to-fuel conversion.

A new series of 1,8-naphtalimides containing an imine bond at the 3-position of the naphthalene ring was synthesized using 1H, 13C NMR, FTIR, and elementary analysis. The impact of the substituent in the imine linkage on the selected properties and bioimaging of the synthesized compounds was studied. They showed a melting temperature in the range of 120–164 °C and underwent thermal decomposition above 280 °C. Based on cyclic and differential pulse voltammetry, the electrochemical behavior of 1,8-naphtalimide derivatives was evaluated. The electrochemical reduction and oxidation processes were observed. The compounds were characterized by a low energy band gap (below 2.60 eV). Their photoluminescence activities were investigated in solution considering the solvent effect, in the aggregated and thin film, and a mixture of poly(N-vinylcarbazole) (PVK) and 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole (PBD) (50:50 wt.%). They demonstrated low emissions due to photoinduced electron transport (PET) occurring in the solution and aggregation, which caused photoluminescence quenching. Some of them exhibited light emission as thin films. They emitted light in the range of 495 to 535 nm, with photoluminescence quantum yield at 4%. Despite the significant overlapping of its absorption range with emission of the PVK:PBD, incomplete Förster energy transfer from the matrix to the luminophore was found. Moreover, its luminescence ability induced by external voltage was tested in the diode with guest–host configuration. The possibility of compound hydrolysis due to the presence of the imine bond was also discussed, which could be of importance in biological studies that evaluate 3-imino-1,8-naphatalimides as imaging tools and fluorescent materials for diagnostic applications and molecular bioimaging.

In this work, the structure–property relationship was investigated for a series of Re(I) carbonyls [ReCl(CO)3(R-terpy-κ2N)], [ReCl(CO)3(R-dtpy-κ2N)], and [ReCl(CO)3(R-dppy-κ2N)]. The studied compou...

A series of 2,6-di(thiazol-2-yl)pyridines (dtpy) functionalized at 4-position with 1-naphtyl (1), 2-naphtyl (2), 9-anthryl (3), 2-anthryl (4), 9-phenantryl (5) and 1-pyrenyl (6) groups has been synthesized and thoroughly investigated. The molecular formulas of 1–6 were determined by 1H and 13C NMR, elemental analysis and X-Ray analysis (1, 3 and 5). In the solid state structures, the dtpy framework shows good planarity, while the aryl substituent is significantly inclined to the central pyridine to minimize inter-ring H⋯H repulsions and hydrogen–π-ring steric repulsions. The nature of excited states involved in the photophysical processes has been explored by carrying out absorption and emission UV–Vis studies in solution and solid state, as well as quantum chemical calculations. Large aryl substituents, such as anthryl and pyrenyl, induce a remarkable red-shift of the absorption and emission bands, in agreement with a stronger π-delocalization. For compounds 3, 4 and 6, which show a large, positive solvatochromism, the excited states gain significant charge transfer (CT) character. The efficiency of the ICT/TICT state formation was found to depend on solvent polarity and torsional hindrance between the aryl and dtpy moieties. To investigate the impact of torsional hindrance on ICT formation, ultrafast pump–probe measurements were performed for compounds 3 and 4. All the synthesized dtpy were electrochemically active and undergo oxidation and reduction processes, as was revealed by CV and DPV measurements. The particular choice of aryl substituent significantly impacts the thermal properties and electroluminescence ability of the investigated 2,6-di(thiazol-2-yl)pyridines.

Alloyed triple A-cation perovskites containing a mixture of Cs, methylammonium (MA), and formamidinium (FA) cations are attracting intense attention because of their high photovoltaic performance a...

Long-period gratings (LPGs) induced in optical fibers show exceptional refractive index (RI) sensitivity and thus they are often applied for label-free biosensing. However, during measurements at changing environmental conditions, the surface of the fiber made of fused silica is subjected to stresses that can cause alterations in its structure. The problem is particularly important when long-term or biosensing measurements are considered and when sensor surface may be exposed to subsequent drying and immersion in aqueous solutions. The aim of this paper was to investigate the influence of sequential drying in air and soaking in water of the fused silica fiber cladding surface on the optical response of LPGs. We demonstrated that transmission spectrum of LPG measured in water before and after drying in air differed significantly and further changed with subsequent drying steps indicating increase of the local RI. All these changes correspond to the alterations in the cladding surface, i.e., its fracturing and pores rearrangement, caused by the stress induced during drying and then immersing in water, as well as possible corrosion and formation of nanosized objects on the cladding surface. The effect can be additionally influenced by washing the samples in organic solvents. We confirmed that measurements done in a flow-cell system, where the sensor was kept wet during the sensing experiment may eliminate the water-induced fiber surface alteration effect and thus minimize the amount of false results. Described findings are highly important for biosensing applications of any optical-fiber-based devices.

Two novel 2,4-difluorenylquinoline derivatives with different length of alkyl chain at fluorene unit (Q-F1 with methyl and Q-F2 with octyl chain) of donor-acceptor (D-A) type were synthesized and comprehensively characterized. The compounds exhibited bright emission in the blue spectral region at 400 nm and high fluorescence efficiency of 63–97% in solution. The EL measurements of OLEDs with Q-F1, and for comparison 2,4-dicarbazolylquinoline (Q-C1) were performed to determine any correlations between the device performance and the different D units at quinoline core. These fluorenyl and carbazolyl substituted quinolines (Q-F1 and Q-C1) were found to display good thermal stability with a decomposition temperature of 301 and 416 °C, respectively. A molecule with carbazole units (Q-C1) dispersed in a host matrix exhibited higher PL quantum yield (15%) compared to Q-F1 (11%). The devices with structure ITO/PDOT:PSS/PVK:PBD:compound/Al with 15 (Q-F1) and 2 (Q-C1) wt. % of compound content in a blend were constructed. The diode based on Q-C1 emitted green light with EL maximum at 550 nm under an applied external voltage. Furthermore, by incorporation of a layer of plasmonically active silver nanowires into the device based on Q-C1 (ITO/PEDOT:PSS + AgNWs/PVK:PBD:Q-C1 (2 wt%)/Al) the noticeably more intense EL signal was detected. These results show that these compounds are promising candidates and may be used in organic light emitting devices.

A series of 2,2′:6′,2″-terpyridine (terpy), 2,6-di(thiazol-2-yl)pyridine (dtpy), and 2,6-di(pyrazin-2-yl)pyridine (dppy) derivatives with electron donating amino groups (dimethylamine, piperidine, morpholine and diphenylamine) connected to the terpy/dtpy/dppy skeleton via phenylene linkage have been thoroughly investigated in order to get an insight into the impact of amine donors and nitrogen-based π-deficient heterocycles on the thermal, redox, UV–Vis absorption and emission properties. All the compounds melted without thermal decomposition and the presence of di(pyrazin-2-yl)pyridine skeleton increased the melting temperature and prevented formation of amorphous material. The obtained compounds undergo electrochemical reduction and oxidation processes and show electrochemically estimated Eg in the range of 2.30–2.83 eV. The lowest values of Eg were confirmed for the compounds bearing 2,6-di(pyrazin-2-yl)pyridine core and dimethylamine or piperidine substituents. Structure-dependent fluorescence properties of the synthesized compounds were evidenced in both solution and solid state. The use of 2,2′:6′,2″-terpyridine as acceptor unit gives opportunity to obtain more efficient emitters, while 2,6-di(pyrazin-2-yl)pyridine derivatives display the largest Stokes shifts. The dramatic decrease in the fluorescence quantum yield with the increasing polarity was attributed to ICT→TICT, while dual emission behavior was assigned to LE to ICT emissions. The effect of protonation and viscosity on the emission properties was also examined and it was found to be dependent on the nature of the acceptor moiety. Under external voltage the 2,6-di(pyrazin-2-yl)pyridine derivatives, except for dtpy with diphenylamine, did not exhibit light emission, contrary to the functionalized terpy and dppy.

Three rhenium(I) carbonyl complexes with 4′-(n-pyridyl)−2,2′:6′,2′′- terpyridines (n-pytpy; n = 2, 3 and 4), coordinated to the central metal in a bidentate mode, have been synthesized in order to explore the impact of 2-, 3- and 4-pyridyl substituents on the thermal, photoluminescent, and electrochemical properties of the isomeric forms of fac-[ReCl(CO)3(n-pytpy-κ2N)]. The molecular formulas of Re(I) compounds were confirmed by 1H and 13C NMR and X-Ray analysis. Thermal properties were determined by differential scanning calorimetry. Electrochemical behaviour was investigated using cyclic voltammetry. The ground and excited state properties of 1–3 were investigated utilizing absorption and emission spectroscopy, and photoluminescence studies were performed both in solution and solid state, as a powder and thin films. In order to gain more insight into the electronic structure of the Re(I) complexes, the density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were performed. Both experimental and theoretical studies indicated MLLCT nature of the emissive state in fac-[ReCl(CO)3(n-pytpy-κ2N)]. The differences in emissive behaviour of 1–3 were correlated with changes in electron-withdrawing properties of the pendant n-pyridyl incorporated into 2,2′:6′,2′′-terpyridine core and changes in the architecture of crystal packing. The ability of the complexes for light emission under external voltage was preliminary tested in devices with configuration ITO/PEDOT:PSS/complex/Al and ITO/PEDOT:PSS/PVK:PBD:complex/Al.

New phenanthro[9,10-d]imidazole derivatives bearing thienyl motifs were prepared by the condensation reaction. They were characterized using elemental analysis and NMR spectroscopy. Thermal, electrochemical, spectroelectrochemical, and optical properties of synthesized compounds were investigated. The prepared compounds were electrochemically active and showed multistep electrochemical reduction and oxidation. Phenanthro[9,10-d]imidazole derivatives exhibited luminescence with emission bands around 400 nm. The photoluminescence quantum yields in solution were found between 41–72%. The photoluminescence of the films, prepared from the synthesized compounds, was observed in the blue range of light. Additionally, the electroluminesce ability of the obtained molecules was preliminary tested.

Three push-pull molecules with linear, quadrupolar and tripodal arrangements, consisting of triphenylamine (electro-donor) substituted with malononitrile groups (electro-acceptor), were synthesized with high yield by a simple procedure. Impact of the number of malononitrile substituents on optoelectronic properties was investigated with cyclic voltammetry, absorption and emission spectroscopy, as well as density functional theory calculation. The derivatives formed amorphous materials and exhibited low energy band gaps ranging from 2.06 to 2.49 eV. UV–Vis absorption and photoluminescence emission spectra were investigated in solutions (CHCl3, NMP) and in solid-state as thin films and two kinds of blends (with PMMA and PVK:PBD). Quantum yield of photoluminescence was dependent on the molecule structure, solvent, and solid-state layer formulation. The compounds exhibited high photoluminescence quantum yield in the range of 15–42% and 12–59% in solid-state as film and blend with PMMA (1 wt%), respectively, being promising for applications in light emitting diodes. The diodes with active layer consisting of neat derivatives and compounds molecularly dispersed in PVK:PBD (50:50 wt%) matrix showed orange and green electroluminescence.

Single nanocrystal spectroscopy is employed to demonstrate metal-enhanced optical response of Er3+/Yb3+ doped up-conversion nanocrystals deposited on graphene upon coupling with silver nanowires. Direct interaction between nanocrystals and graphene results in quenching of up-conversion emission and shortening of luminescence decay times, due to the energy transfer to graphene. The amount of the energy absorbed by graphene can be enhanced by coupling Er3+/Yb3+ doped up-conversion nanocrystals with silver nanowires. Microscopy studies with high spatial resolution together with time-resolved analysis of nanocrystal luminescence show increase of the emission rates with fourfold enhancement of the intensity for nanocrystals placed in the vicinity of silver nanowires. This strong enhancement emerges despite simultaneous interaction with graphene. The hybrid nanostructure provides thus a way to combine optical activity of up-conversion nanocrystals and enhancement provided by metallic nanowires with excellent electrical and mechanical properties of graphene.

In this paper, we describe both new as well as described in our previous works 1,8-naphthalimide derivatives substituted at the 3-C position with imine or β-ketoenamine unit in order to demonstrate a broader scope of research enabling of analysis between the structure-properties relationship relevant to the application of these compounds in organic electronics and cellular imaging. Thermal, physicochemical, optical, electrochemical, electroluminescence, and biological properties of a series of derivatives containing the 1,8-naphthalimide unit were tested and compared. This allowed the determination of the impact of substituents in the imide part (hexylamine, phenylethyl, benzyl, fluorobenzyl, methylbenzyl), type of bond (imine or ketoenamine) as well as the substituent on the naphthalene ring (2-hydroxyphenyl, 5-bromo-2-hydroxyphenyl, 3,5-diodo-2-hydroxyphenyl, pyrimidines) on their properties. Moreover, the properties in the aggregating state were tested in the MeOH/PBS system. Imines are susceptible to the hydrolysis process and aggregation-caused photoluminescence quenching (ACQ). In turn, β-ketoenamine shown excited-state intramolecular proton transfer promoted by aggregation (AIEE). Our studies can be helpful in the further design of compounds containing the 1,8-naphthalimide structure for various applications.

In the current work, comprehensive photophysical and electrochemical studies were performed for eight rhenium(I) complexes incorporating 2,2′:6′,2″-terpyridine (terpy) and 2,6-bis(pyrazin-2-yl)pyridine (dppy) with appended 1-naphthyl-, 2-naphthyl-, 9-phenanthrenyl, and 1-pyrenyl groups. Naphthyl and phenanthrenyl substituents marginally affected the energy of the MLCT absorption and emission bands, signaling a weak electronic coupling of the appended aryl group with the Re(I) center. The triplet MLCT state in these complexes is so low lying relative to the triplet 3ILaryl that the thermal population of the triplet excited state delocalized on the organic chromophore is ineffective. The attachment of the electron-rich pyrenyl group resulted in a noticeable red shift and a significant increase in molar absorption coefficients of the lowest energy absorption of the resulting Re(I) complexes due to the contribution of intraligand charge-transfer (ILCT) transitions occurring from the pyrenyl substituent to the terpy/dppy core. At 77 K, the excited states of [ReCl(CO)3(Ln-κ2N)] with 1-pyrenyl-functionalized ligands were found to have predominant 3ILpyrene/3ILCTpyrene→terpy character. The 3IL/3ILCT nature of the lowest energy excited state of [ReCl(CO)3(4′-(1-pyrenyl)-terpy-κ2N)] was also evidenced by nanosecond transient absorption and time-resolved emission spectroscopy. Enhanced room-temperature emission lifetimes of the complexes [ReCl(CO)3(Ln-κ2N)] with 1-pyrenyl-substituted ligands are indicative of the thermal activation between 3MLCT and 3IL/3ILCT excited states. Deactivation pathways occurring upon light excitation in [ReCl(CO)3(4′-(1-naphthyl)-terpy-κ2N)] and [ReCl(CO)3(4′-(1-pyrenyl)-terpy-κ2N)] were determined by femtosecond transient absorption studies., A series of eight rhenium(I) complexes with 2,2′:6′,2″-terpyridine (terpy) and 2,6-di(pyrazin-2-yl)pyridine (dppy) substituted with 1-naphthyl, 2-naphthyl, 9-phenanthrenyl, and 1-pyrenyl groups was synthesized, and the effect of the tris-heterocyclic core and aryl substituent on selected properties of the obtained [ReCl(CO)3(Ln-κ2N)] was studied in detail. The complexes [ReCl(CO)3(Ln-κ2N)] with 1-pyrenyl-subsituted ligands exhibited greatly enhanced room-temperature photoluminescence lifetimes, consistent with the formation of an equilibrium between the 3MLCT and 3IL/3ILCT excited states.

In this work, a series of six rhenium(I) complexes bearing 2,2′:6′,2″-terpyridine (terpy), 2,6-di(thiazol-2-yl)pyridine (dtpy), and 2,6-di(pyrazin-2-yl)pyridine (dppy) with appended quinolin-2-yl and N-ethylcarbazol-3-yl groups were prepared and spectroscopically investigated to evaluate the photophysical consequences of both the trisheterocyclic core (terpy, dtpy and dppy) and the heterocyclic substituent. The [ReCl(CO)3(Ln-κ2N)] complexes are regarded as ideal candidates for getting structure–property relationships, while terpy-like framework represents an excellent structural backbone for structural modifications. The replacement of the peripheral pyridine rings of 2,2′:6′,2″-terpyridine by thiazoles and pyrazines resulted in a significant red-shift of the absorption and emission of [ReCl(CO)3(Ln-κ2N)] due to stabilization of the ligand-centred LUMO orbital. Both quinoline and N-ethylcarbazole are extended π-conjugation organic chromophores, but they differ in electron-donating abilities. The low-energy absorption band of Re(I) complexes with the triimine ligands bearing quinolin-2-yl group was contributed by the metal-to-ligand charge-transfer (MLCT) electronic transitions. The introduction of electron-donating N-ethylcarbazol-3-yl substituent into the triimine acceptor core resulted in the change of the character of the HOMO of Re(I) complexes and a significant increase of molar absorption coefficients of the long-wavelength absorption, which was assigned to a combination of 1MLCT and 1ILCT (intraligand charge-transfer) transitions. Regardless of the appended heteroaromatic group, the emitting excited state of Re(I) terpy-based complexes was demonstrated to have predominant 3MLCT character, as evidenced by comprehensive studies including static and time-resolved emission spectroscopy along with ultrafast transient absorption measurements. The diodes with Re(I) complexes dispersed molecularly in a PVK:PBD matrix were emissive and effects of the complex structure on colour of emitted light and its intensity was pronounced.

We demonstrate that single functionalized silver nanowires form a geometric platform suitable for efficient real-time detection of single photoactive proteins. By collecting series of images using wide-field fluorescence microscopy, events of single protein attachment can be distinguished with the signal to noise ratio further improved by fluorescence enhancement due to plasmon excitations in the nanowires. The enhancement is evidenced by strong shortening of the fluorescence decay of single photoactive proteins conjugated to the silver nanowires.

Three Re(i) carbonyl complexes [ReCl(CO)3(Ln)] bearing 2,2'-bipyridine, 2,2':6',2''-terpyridine, and 1,10-phenanthroline functionalized with diphenylamine/or triphenylamine units (L1-L3) were synthesized to explore the impact of highly electron donating units appended to the imine ligand on the thermal and optoelectronic properties of Re(i) systems. Additionally, for comparison, the ligands L1-3 and parent complexes [ReCl(CO)3(bipy)], [ReCl(CO)3(phen)] and [ReCl(CO)3(terpy-κ2N)] were investigated. The thermal stability was evaluated by differential scanning calorimetry. The ground- and excited-state electronic properties of the Re(i) complexes were studied by cyclic voltammetry and differential pulse voltammetry, absorption and emission spectroscopy, as well as using density-functional theory (DFT). The majority of the compounds form amorphous molecular materials with high glass transition temperatures above 100 °C. Compared to the unsubstituted complexes [ReCl(CO)3(bipy)], [ReCl(CO)3(phen)] and [ReCl(CO)3(terpy-κ2N)], the HOMO-LUMO gap of the corresponding Re(i) systems bearing modified imine ligands is reduced, and the decrease in the value of the ΔEH-L is mainly caused by the increase in HOMO energy level. In relation to the parent complexes, all designed Re(i) carbonyls were found to show enhanced photoluminescence, both in solution and in solid state. The investigated ligands and complexes were also preliminarily tested as luminophores in light emitting diodes with the structures ITO/PEDOT:PSS/compound/Al and ITO/PEDOT:PSS/PVK:PBD:compound/Al. The pronounced effect of the ligand chemical structure on electroluminescence ability was clearly visible.

The effects of combining naturally evolved photosynthetic pigment–protein complexes with inorganic functional materials, especially plasmonically active metallic nanostructures, have been a widely studied topic in the last few decades. Besides other applications, it seems to be reasonable using such hybrid systems for designing future biomimetic solar cells. In this paper, we describe selected results that point out to various aspects of the interactions between photosynthetic complexes and plasmonic excitations in Silver Island Films (SIFs). In addition to simple light-harvesting complexes, like peridinin-chlorophyll-protein (PCP) or the Fenna–Matthews–Olson (FMO) complex, we also discuss the properties of large, photosynthetic reaction centers (RCs) and Photosystem I (PSI)—both prokaryotic PSI core complexes and eukaryotic PSI supercomplexes with attached antenna clusters (PSI-LHCI)—deposited on SIF substrates.

Since the norovirus is the main cause of acute gastroenteritis all over the world, its fast detection is crucial in medical diagnostics. In this work, a rapid, sensitive, and selective optical fiber biosensor for the detection of norovirus virus-like particles (VLPs) is reported. The sensor is based on highly sensitive long-period fiber gratings (LPFGs) coated with antibodies against the main coat protein of the norovirus. Several modification methods were verified to obtain reliable immobilization of protein receptors on the LPFG surface. We were able to detect 1 ng/mL norovirus VLPs in a 40-min assay in a label-free manner. Thanks to the application of an optical fiber as the sensor, there is a possibility to increase the user&rsquo, s safety by separating the measurement point from the signal processing setup. Moreover, our sensor is small and light, and the proposed assay is straightforward. The designed LPFG-based biosensor could be applied in both fast norovirus detection and in vaccine testing.

Series of Re(I) carbonyls complexes were designed and synthesized to explore the impact of the triimine skeleton and number of methoxy groups attached to aryl substituents on their optoelectronic and thermal properties. The chemical structures of the prepared complexes were confirmed by 1H and 13C NMR spectroscopy, HR-MS, elemental anlsysis, and X-ray measurements. DSC measuremtns showed that they melted in the range of 198–325 °C. Some of them form stable molecular glasses with high glass transition temperatures (158–173 °C). Experimentally obtained optical properties were supported by DFT calculations. The UV–Vis spectra display a series of overlapping absorption bands in the range 200–350 nm, and much weaker broad band in the visible spectral region, due to intraligand and charge transfer transitions, respectively. All synthesized complexes were emissive in solution and in solid state as powder. Moreover, when applied in diodes, some of them exhibited ability for emission of light under external voltage with maximum of electroluminescence band located at 591–630 nm.

Three novel perylene diimide derivatives with bulky aromatic moieties (fluorene, carbazolyl-fluorene, and anthracyl-fluorene) connected via triple bonds with perylene core were successfully designed and synthesized. The chemical structure of prepared compounds was confirmed by 1H and 13C NMR and mass spectrometry. Their optimized ground-state geometry and frontier molecular orbitals were theoretically estimated based on density functional theory. The compounds undergo the reversible electrochemical reduction process and exhibit very low energy band gaps (1.56–1.98 eV) being promising for electronic applications. They also display excellent solubility, high thermal stability and luminescence in solution and in the solid state as a film in the red spectral region. The highest photoluminescence quantum yield (79% in solution and 28% in the film) was found for perylene diimide bearing fluorene unit. All molecules showed the ability for light emission under an applied voltage. The fabricated diodes with structure ITO/PEDOT:PSS/compound/Al exhibited electroluminescence with maximum emission band located between 685 and 732 nm. The most intense electroluminescence, which was additionally plasmonically enhanced by incorporating silver nanowires, was observed for the device based on molecules with anthracene structure.

Novel 1,8-naphthalimides core substituted at 3-C position via imine bond with carbazole, benzothiazole, methylindole, quinoline, benzoindole, phenylmorpholine and triphenylamine derivatives were designed, synthesized and investigated with regard to their thermal, electrochemical, and luminescence behavior. DSC measurements showed that the obtained crystalline compounds can be converted into amorphous materials with glass transition temperatures in the range of 28–54 °C, except for the molecule bearing benzoindole derivative. The prepared compounds were thermally stable with the onset of thermal decomposition in the range of 345–368 °C. Energy band gap electrochemically estimated was modulated from 2.13 to 2.52 eV. Effect of excitation wavelength on the photoluminescence relative intensity of those naphthalimides in solution was detected. Their photoluminescence maximum band was located in the range of 495–560 nm in solution with the quantum yield from 0.2 to 14.0%. In the film, they emitted light in the blue and green spectral region with quantum yields from 1.1 to 3.6%. The electroluminescence ability of core substituted 1,8-naphthalimides was tested in the single-layer diode geometry. They were utilized as an emitting layer for both non-doped and doped single-layer OLEDs fabricated by solution processing. Additionally, calculations using density functional theory were performed to obtain the optimized ground-state geometry and distribution of the HOMO and LUMO levels of the synthesized molecules.

We demonstrate fast and simple route to selective virus detection using antibody-functionalized silver nanowires. While the immunocomplex formation takes place in solution, the presence of viruses is determined by correlating transmission and fluorescence images obtained after depositing nanowire solution on a substrate. Importantly, by mixing nanowires in solution we expect to substantially increase the probability for immunocomplex formation, as evidenced by almost complete capturing of viruses after overnight incubation. This approach, based on dynamic search for viruses in solution, gives the possibility to reach medically relevant detection level of 103 pfu/ml, which translates to just 5 bacteriophages in a test volume of 5 μl.

A series of molecules with a dicyanovinyl acceptor connected with various substituted phenyls as donor blocks were synthesized and characterized. The thermal, electrochemical and photophysical properties of these compounds were investigated and compared. DSC and TGA measurements revealed that all compounds showed high both different melting transitions and the beginning of decomposition. The electrochemical studies did not show significant differences in energy band gap being between 2.41 and 2.55 eV (except for one with carbazole unit), which was also supported by the density functional theory calculations. They emitted light with higher photoluminescence quantum yield in film than in solution. Blends containing the malononitrile derivatives dispersed in a solid matrix consisting of poly(9-vinylcarbazole) and (2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole) emitted with small or high contribution from the host, signaling efficient or incomplete energy transfer from host to guest molecules. Emission of light under external voltage by diodes based on these blends was observed.

Two cyclometalated alkynylgold(III) complexes [AuCl(tpy)(C≡C–C6H4CH3)] (1) and [AuCl(ppy)(C≡C–C6H4CH3)] (2), where ppy = 2-phenylpyridine and tpy = 2-(p-tolyl)-pyridine, were successfully synthetized. Their photophysical properties were investigated by absorption and photoluminescence spectroscopy in solution, solid state, and glass matrix (77 K). Differences in solid state luminescent behaviour of the reported Au(III) complexes were correlated with packing of [AuCl(tpy)(C≡C–C6H4CH3)] and [AuCl(ppy)(C≡C–C6H4CH3)] molecules and weak interactions in the network lattices of 1 and 2. Additionally, photoluminescence spectra of [AuCl(tpy)(C≡C–C6H4CH3)] in film and dispersed in solid matrix consisting of poly(9-vinylcarbazole) and (2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole) were registered. The preliminary tests of electroluminescence ability of complex 1 were carried out.

A series of solution-processable tetrasubstituted naphthalene derivatives bearing thiophene or carbazole units were synthesized using the tandem cycloaddition [2+1+2+1] and Diels–Alder reaction[4+2]. Thermal, electrochemical, absorption, and emission properties of synthesized compounds were studied. They can be considered as molecular glasses with glass transition temperature ranging from 37 to 122 °C with high thermal stability up to 300 or 400 °C. The naphthalene derivatives were electrochemically active and showed low energy band gap between 1.64 and 1.85 eV. All derivatives were luminescent and emitted light with maximum emission band located at 379–436 nm with photoluminescence quantum yield in the range of 9.5–19.8% in solution. They photo- and electroluminescence ability in solid state as thin film and blends with poly(9-vinylcarbazole) (PVK) and mixture PVK with (2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole) (PBD) were tested. Together with increase of compound content from 2 to 15 wt% in binary matrix, the increase of electroluminescence intensity was observed. Diodes with guest-host configuration showed electroluminescence with maximum of emission band from 593 to 637 nm. The most intense emission of light under applied voltage characterized devices based on compound bearing carbazole derivatives and one methyl group.

Solid-state emissive organic materials are perspective for applications in organic electronics. Here, the 2,2-dicyanovinyl derivatives bearing thiophene, furan, phenyl, N-methylpyrrole, naphthalene, benzothiophene and benzofuran structures were successfully prepared by the Knoevenagel condensation of propane-1,3-dinitrile with various ketones. The synthesized compounds were crystalline solid with melting temperature between 87 and 161 °C and temperature of 5% weight loss in the range of 140–190 °C based on differential scanning calorimetry and thermogravimetric measurements, respectively. The density functional theory showed that LUMO orbitals are localized more at 2,2-dicyanovinyl moiety whereas in the case of HOMOs slightly higher contribution from the aromatic parts can be observed. The results of cyclic voltammetry showed that both reduction and oxidation process values differ greatly depending on donor properties. Calculated the ionization potentials and electron affinities were in the range of −5.52 – −6.48 eV and −3.3 − −3.64 eV, respectively, which results in energy band gap mainly below 3.0 eV. The 2,2-dicyanovinyl derivatives were emissive both in solution and in the solid, in which higher quantum photoluminescence yield was detected. When 2,2-dicyanovinyl derivatives molecularly dispersed in a solid matrix poly(9-vinylcarbazole) (PVK) and a binary matrix consisting of PVK (60 wt. %) and 2- text-butylphenyl-5-biphenyl-1,3,4-oxadiazole) (PBD) (40 wt. %) (guest-host configuration), they show green or yellow or red electroluminescence.

Multimodal polymer encapsulated CdSe/Fe3O4 nanoplatforms with dual optical and magnetic properties have been fabricated. We demonstrate that CdSe/Fe3O4 nanocapsules (NCs) upon excitation with UV radiation or NIR fs-laser excitation exhibit intense one- or two-photon emission at 535 nm, whereas the combination of an alternating magnetic field and 808 nm IR laser excitation results in heat generation. Since anticancer therapies require relatively high doses of Fe3O4 nanoparticles (NPs) to induce biologically relevant temperature jumps, the therapeutic effects of 0.1 and 1 mg/mL Fe3O4 NCs and CdSe/Fe3O4 NCs were investigated using breast cancer cell lines, ER-positive MCF-7, and triple-negative MDA-MB-231 cells. Improved biocompatibility of CdSe/Fe3O4 NCs compared to Fe3O4 NCs was revealed at higher NCs concentration suggesting safe potential medical applications of CdSe/Fe3O4 NCs. In contrast, 1 mg/mL Fe3O4 NCs were found to be more cytotoxic to MDA-MB-231 than MCF-7 cells through iron-induced oxidative stress, lipid peroxidation, and concomitant ferroptotic cell death. We believe that Fe3O4 NCs-mediated cellular response may be heterogeneous that reflects, at least in part, cancer cell genotype, molecular phenotype, and pathological classification.

Six novel azomethines with substituted thiophene central core were synthesized and their properties are reported. They were obtained by the condensation reaction between 2,5-diamino-thiophene-3,4-dicarboxylic acid diethyl ester and various aldehydes. The imines were characterized by NMR and FTIR spectroscopies and by elemental analysis. DSC measurements revealed that the prepared compounds are molecular glasses (except for one) with high T g varying from 94 and 183 °C. Their redox properties were investigated in solution by cyclic voltammetry and differential pulse voltammetry. It was found that all imines were electrochemically active and showed low values of energy band gap ranging from 1.61 to 1.78 eV. Photoluminescence measurements indicated that they emitted light in solution with quantum yield (Φ PL ) in the range of 1.2–14.3% and in solid state as film and blend with poly(methyl methacrylate) and binary blend with poly(9-vinylcarbazole) (PVK) and (2-(4-tert-butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole) (PDB) with Φ PL form 0.24–1.77% and from 0.52% to 1.66%, respectively. The density functional theory (DFT) was applied for calculating their geometries and frontier molecular orbitals. Their electroluminescence ability was examined in guest-host diode with structure ITO/PEDOT:PSS/PVK:PBD:imine / Al and emission of light with maximum of emission band from 626 to 674 nm was observed. This work demonstrates, to the best of our knowledge, the first example of light emitting devices based on thiophene azomethines as active layer component.

Novel derivatives of 4'-phenyl-2,2':6′,2″-terpyridine (tpy) with ethynyl ( T1 ), 2-ethynyl-9,9-dioctylfluorene ( T2 ), 9,9-dioctylfluorene ( T3 ), 9-ethynyl-10-decyloxyanthracene ( T4 ) substituents were obtained via Sonogashira or Suzuki-Miyaura coupling reactions, respectively, and thoroughly characterized. The presence of ethynyl bridge impacts photophysical properties of novel compounds by shifting absorption and emission spectra towards longer wavelengths as compared to T3 , where fluorene is connected with tpy via a single bond. TGA measurements showed that among the new terpyridines those obtained as solids exhibited high thermal stability as opposed to those which were oils (tpy containing fluorene motif). Due to the fact that high thermal stability of 4'-phenyl-2,2':6′,2″-terpyridine derivatives showed photoluminescence (PL) quantum yield (Φ) in the range of 27–84% in solution, their electroluminescence ability was tested in diodes with guest-host configuration. For the compounds dispersed in a matrix consisting of poly(9-vinylcarbazole) (PVK) (50 wt %) and (2- tert -butylphenyl-5-biphenyl-1,3,4-oxadiazole) (PBD) (50 wt %) radiation with maxima between 374 and 531 nm and characterized with Φ in the range of 8–12% was observed. They exhibited green or violet electroluminescence. The results confirmed the substantial role of aryl groups and the linker in the presented terpyridines in terms of their thermal, electrochemical, optical and electroluminescence properties. In addition, density functional theory (DFT) and time-dependent-density functional theory (TD-DFT) calculations were performed to provide an independent support and deeper insight into the experimental results.

Five novel derivatives of pyrene, substituted at positions 1,3,6,8 with 4-(2,2-dimethylpropyloxy)pyridine (P1), 4-decyloxypyridine (P2), 4-pentylpyridine (P3), 1-decyl-1,2,3-triazole (P4), and 1-benzyl-1,2,3-triazole (P5), are obtained through a Suzuki-Miyaura cross-coupling reaction or CuI -catalyzed 1,3-dipolar cycloaddition reaction, respectively, and characterized thoroughly. TGA measurements reveal the high thermal stability of the compounds. Pyrene derivatives P1-P5 all show photoluminescence (PL) quantum yields (Φ) of approximately 75 % in solution. Solid-state photo- and electroluminescence characteristics of selected compounds as organic light-emitting diodes are tested. In the guest-host configuration, two matrixes, that is, poly(N-vinylcarbazole) (PVK) and a binary matrix consisting of PVK and 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole (PBD) (50:50 wt %), are applied. The diodes show red, green, or blue electroluminescence, depending on both the compound chemical structure and the actual device architecture. In addition, theoretical studies (DFT and TD-DFT) provide a deeper understanding of the experimental results.