Fluorescence Band Research Articles

Synthesis, Structure, Spectral and Redox Properties of Phenoxazine Embedded Heteroporphyrins

A series of phenoxazine embedded heteroporphyrins containing one phenoxazine, two pyrroles and one heterocycle, such as furan, thiophene, selenophene and telluorophene, connected through four meso carbon atoms were synthesized by condensing one equivalent of phenoxazine‐based tripyrrane with one equivalent of the appropriate 2,5‐bis(hydroxymethyl‐p‐tolyl) heterocycle under acid‐catalyzed conditions, and their structure, spectral and electrochemical properties were compared with those of previously reported phenothiazine embedded heteroporphyrins. The X‐ray crystal structure of the phenoxazine embedded selenoporphyrin revealed that the selenophene ring, which is opposite phenoxazine moiety, points outward from the macrocyclic core, and the phenoxazine unit deviated by an angle of 39.47° from the mean plane defined by the four meso carbons atoms. The replacement of the phenothiazine unit in phenothiazine embedded heteroporphyrins with a phenoxazine unit led to significant alteration of the electronic properties of the macrocycles, as reflected in their spectral and electrochemical properties. The absorption spectra of phenoxazine embedded heteroporphyrins showed bathochromically shifted absorption bands, hypsochromically shifted fluorescence bands with decent quantum yields, more facile oxidation and more difficult reduction as compared to the corresponding phenothiazine embedded heteroporphyrins. DFT and TD‐DFT studies were in support of the experimental observations.

Self-Assembly of Metallo-Supramolecular Amphiphiles Based on Azadipyrromethenes: Consecutive Pathways to Nanodiscs and Nanosheets.

A new class of metallo-supramolecular amphiphilic dyes 1a, b was constructed by using two azadipyrromethene units which were respectively modified with two hydrophobic alkyl and two hydrophilic oligo(ethylene glycol) chains. The spectroscopic and morphological studies revealed the consecutive self-assembly pathways of 1a in EtOH/H2O mixed solvent. The monomers of 1a firstly aggregated into the kinetic-controlled, nanodisc-shaped Agg. I upon cooling and the latter spontaneously transformed into the thermodynamically more stable Agg. II with a nanosheet morphology. While the non-fluorescent Agg. I displayed a broad absorption band (λmax = 594 nm), the Agg. II displayed a more intensive and narrowed J-band (λmax =693 nm) and a fluorescence band with a maximum at 760 nm (Фfl = 0.1), which could be ascribed to the J-aggregation induced emission enhancement. The kinetics of Agg. I to Agg. II transformation was further modulated by seed-initiated supramolecular polymerization with various ratios of Seedagg.II, in which the transformation rate was significantly increased by ca. 2 orders of magnitude compared to the spontaneous process. The supramolecular amphiphile 1b bearing longer hydrophilic chains formed only one type aggregate, which exhibited spectroscopic and morphological properties that were highly comparable with that of Agg. I.

Differentiating the Aβ42 aggregation states via intrinsic tyrosine fluorescence spectrum

Aggregation of amyloid β-peptide (Aβ) into β-sheet-rich fibrils is central to the development of Alzheimer’s disease, with Aβ42 more prone to aggregation over Aβ40. Using the intrinsic tyrosine fluorescence spectrum, we show that Aβ42 exhibits a biphasic fluorescence pattern featuring a broad band and a narrow one, distinct from Aβ40 and dissolved tyrosine. Molecular dynamics simulations highlighted the differences in tyrosine’s rotamer populations and dynamics between dissolved and aggregated amyloids. Fibrillar Aβ42 shows slower, more uniform tyrosine rotations, corresponding to the narrower fluorescence band. This approach offers a rapid means to differentiate Aβ42 aggregates, benefiting Aβ-related research.

Investigation of H-Bonding and pH on the Fluorescence Spectral Behavior of Valsartan.

The photophysical properties of valsartan (VAL), a potent phenyl tetrazole derivative sartan, were investigated. Valsartan has absorption bands at 230nm and 255nm and a fluorescence band at about [Formula: see text] = 346nm in butanol which is red shifted depending on the H-bonding capability of the solvent. The role of H-bonding in the excited state was approved through the linear correlation of the emission energy of VAL with Camlet-Taft acidity and basicity parameters, α and β, of polar protic solvents. The position and intensity of fluorescence emission bands of VAL are found to be pH dependent, shifting from 425nm at pH 2 to 375nm at pH 4 with enhancement of intermolecular H-bonding and fluorescence intensity depletion beyond pH 5 with formation of tetrazole anion. The results were supported by time-resolved fluorescence measurements which indicated the presence of different species with different lifetimes in the excited state depending on solution pH value. Computational results based on time dependent density functional methods (TDDFT) show that the tetrazole moiety is involved in the [Formula: see text] absorption transitions, while natural bond analysis (NBO) shows that VAL adopts a dimer conformation in water because of effective intermolecular H-bonding.

Double-stranded binuclear helical complexes of 5,5’-bisdiazo-dipyrromethane with Zn(II): synthesis, structures, photophysical properties, and DFT calculations

The reaction of two 5,5΄-bisdiazo-dipyrromethane compounds (H2L1 and H2L2 ) with ZnCl2 afford two Zn(II) complexes (Zn2 L 2 1 and Zn2 L 2 2 ). The X-ray crystallographic studies revealed that both complexes were double-stranded binuclear helicates. Each Zn(II) ion was coordinated to four nitrogen atoms of two azopyrrole units from two ligands in a distorted tetrahedral geometry. Due to the existence of the hydroxyl groups, the Zn2 L 2 2 complex self-assembled into a two-fold interpenetrating grid structure through O-H…O and N-H…O hydrogen bonds. Zn2 L 2 1 and Zn2 L 2 2 displayed intense absorptions at 439 and 446 nm and shoulder peaks at 486 and 497 nm, respectively. Both complexes were also weakly fluorescent with a fluorescence band at 602 nm. DFT calculations revealed that the hydroxyl group can destabilize the frontier molecular orbitals and decrease the energy gap (ΔE), and finally caused Zn2 L 2 2 higher HOMO and LUMO orbital levels, smaller energy gap (ΔE), and longer λmax absorption than Zn2 L 2 1 .

Karyotype's Rearrangement in Some Hybrids of the Orchidinae Subtribe.

Based on our karyological findings in the Anacamptis Rich., Ophrys L., and Serapias L. genera, we have identified chromosomal markers within some hybrids and elucidated their interrelationships. Mitotic chromosomes of fifteen taxa were analyzed using the conventional Feulgen staining method. Only for Anacamptis ×gennarii (Rchb. f.) H.Kretzschmar, Eccarius & Dietr. [A. morio (L.) R.M.Bateman, Pridgeon & M.W.Chase × A. papilionacea (L.) R.M.Bateman, Pridgeon & M.W.Chase] and its parental species were some data obtained and reported with the banding method with Giemsa, Hoechst 33258 fluorochrome, and the FISH techniques. Our research involved new chromosomal measurements of fifteen taxa, including six hybrids, along with schematic representations. Morphometric parameters, i.e., MCA and CVCL, were used to evaluate karyotype asymmetry. Of meaning were the analyses performed on chromosomal complements of selected hybrids, which distinctly revealed marker chromosomes present in one or both putative parental species. Among the parents identified in some hybrids, Ophrys tenthredinifera Willd. has shown some interest due to the presence in its karyotype of a pair of chromosomes (n.1) showing a notable secondary constriction on the long arm. Indeed, one of the homologs is clearly distinguishable in the analyzed hybrids, where it clearly emerges as one of the putative parents. Given the challenges in detecting certain karyomorphological features within the Orchidinae subtribe using alternative methods, such as Giemsa C-banding or fluorescence banding, the Feulgen method remains valuable for cytogenetic characterization. It helps us to understand the genomes of hybrids and parental species, thus contributing to a deeper understanding of their genetic composition.

Turn-On Fluorescence Probe for Cancer-Related γ-Glutamyltranspeptidase Detection.

The design and development of fluorescent materials for detecting cancer-related enzymes are crucial for cancer diagnosis and treatment. Herein, we present a substituted rhodamine derivative for the chromogenic and fluorogenic detection of the cancer-relevant enzyme γ-glutamyltranspeptidase (GGT). Initially, the probe is non-chromic and non-emissive due to its spirolactam form, which hinders extensive electronic delocalization over broader pathway. However, selective enzymatic cleavage of the side-coupled group triggers spirolactam ring opening, resulting in electronic flow across the rhodamine skeleton, and reduces the band gap for low-energy electronic transitions. This transformation turns the reaction mixture from colorless to intense pink, with prominent UV and fluorescence bands. The sensor's selectivity was tested against various human enzymes, including urease, alkaline phosphatase, acetylcholinesterase, tyrosinase, and cyclooxygenase, and showed no response. Absorption and fluorescence titration analyses of the probe upon incremental addition of GGT into the probe solution revealed a consistent increase in both absorption and emission spectra, along with intensified pink coloration. The cellular toxicity of the receptor was evaluated using the MTT assay, and bioimaging analysis was performed on BHK-21 cells, which produced bright red fluorescence, demonstrating the probe's excellent cell penetration and digestion capabilities for intracellular analytical detection. Molecular docking results supported the fact that probe-4 made stable interactions with the GGT active site residues.

Assessment of OH femtosecond thermally assisted fluorescence thermometry for hydrogen non-premixed flames

In this work, we further developed the planar temperature measurement method based on thermally assisted laser-induced fluorescence (TALF) with a single femtosecond (fs) laser and investigated the temperature distribution in the nitrogen-diluted oxygen–hydrogen cross-jet non-premixed flames at 1 kHz. Fs-TALF thermometry was firstly calibrated and assessed in a series of unconfined methane/air laminar flames at atmospheric pressure. In the calibration process, although the calibrated energy difference between OH v′ = 0 and 1 energy level was different from the theoretical value, the measured fluorescence ratio accurately reflected the temperature change from 1600 K to 2200 K in different methane flames. By comparing the calculated OH fluorescence spectrum, we believed that the main reason was the overlap of the OH (1-1) and (0-0) fluorescence bands. After the calibration, experiments were conducted with changing hydrogen flow velocity from 60 to 100 m/s and constant oxidizer flow velocity, where the dilution ratio, D varies from 0.46 to 0.7, and the equivalence ratio, ϕ, varies from 0.5 to 0.9. It is found, within the calibration range, fs-TALF thermometry can correctly measure the flame temperature. However, with ϕ further increases, the difference between the measured and theoretical temperatures gradually increases. At the same time, it was noted that the error in the measured temperature rises gradually as D decreases. In conclusion, fs-TALF thermometry can measure turbulent non-premixed hydrogen flames accurately in a range of temperature with acceptable temporal and partial resolution, while the errors within 200 K and spatial resolution is 170μm. The main error source should be the collisional effect due to the different local concentration of N2 and H2O. The results of this work will contribute to the further development the temperature measurement method hydrogen turbulent flames.

Effect of different thermal processing methods and thermal core temperatures on the protein structure and in vitro digestive characteristics of beef

This study aimed to investigate the effect of different thermal processing treatments on the protein digestion characteristics of beef. The beef samples were subjected to different cooking methods, namely steaming, boiling, and roasting, and different core temperatures (75 °C, 80 °C, 85 °C, and 90 °C), and were subjected to in vitro gastrointestinal digestion simulation. All the thermal processing treatments increased the protein digestibility; the samples that were steamed at 85 °C (S85), boiled at 80 °C (B80), and roasted at 80 °C (R80) showed the biggest gains. The S85 released more peptide species after gastrointestinal digestion, according to peptididomic studies. These differences were closely related to protein structure. Thermal processing treatments resulted in a higher degree of proteolysis and looser protein conformation, as evidenced by decreased intrinsic fluorescence and electrophoretic band intensity, increased surface hydrophobicity, and the change in protein secondary structure from α-helix to β-sheet and random coil. Based on the results, S85 was identified as the optimal thermal processing treatment for enhancing the digestibility of beef protein. The results provide valuable insights into the nutritional qualities and digestion of heat-processed beef protein.

Fluorescent sphalerite rich in tungsten, copper, gallium, silver, and other elements from the Cordilleran-style, polymetallic veins of Philipsburg, Montana

Sphalerite from the central, high-sulfidation zone (enargite-stable) of the Philipsburg polymetallic mining district, southwest Montana, displays unusually bright fluorescence (red, orange, yellow, blue, purple, green) under longwave UV light (365 nm). LA-ICP-MS analysis reveals the fluorescent sphalerite has very low Fe (average < 100 ppm) and variable content of other trace elements that correlate to luminescence color banding. Mean/maximum content (in ppm) in fluorescent sphalerite for selected elements are 5.7/7900 Ag, 107/11800 As, 1400/4730 Cd, 917/30400 Cu, 381/5000 Ga, 32/696 Ge, 119/2130 In, 230/8190 Mn, 43/3000 Pb, 16/1700 Sb, and 89/1980 W. This study is the first to document elevated tungsten content (>10 ppm) in sphalerite. Copper is closely correlated with Ga, consistent with the coupled substitution: Cu+ + Ga3+ = 2Zn2+. Similar coupled substitution reactions can be written for Ag+, In3+, As3+, Sb3+, Bi3+, and Ge4+. However, the brightest red fluorescent bands are most closely related to the unexpected presence of W. Sphalerite with high Cu and Ga but lacking W fluoresces yellow and shows a single Raman peak at 349 cm−1 corresponding to pure sphalerite. In contrast, red-fluorescent sphalerite shows the presence of a second peak at 427 cm−1 that increases in intensity with increased W content. We propose that tungsten enters the sphalerite lattice as W6+ via a substitution such as W6+ + 4Cu+ = 5Zn2+ and that this substitution creates lattice strain that results in the anomalous fluorescence and Raman signals. Sphalerite bands with low concentrations of Cu and Ga fluoresce blue or green. Vivid blue fluorescence is displayed by sphalerite with high Cd (>1000 ppm) but low concentrations of all other trace elements. Sphalerite from the low-sulfidation peripheral mines of the Philipsburg district contains high Fe (>10,000 ppm) and does not fluoresce. Nonetheless, this sphalerite is also highly enriched in trace metals, including Ag (mean 2480/max 8660 ppm), Cu (1610/3440), Mn (7020/8100), and Sb (1960/6390). The results of this study underscore the importance of including tungsten in the list of analytes in future studies of trace elements in sphalerite. In addition, a hand-held UV lamp may be a rapid and cost-effective method to screen sphalerite of variable composition in outcrop or drill core. It may be a useful exploration tool to vector towards a high-sulfidation zone of a zoned porphyry or epithermal deposit, when it is present.

A Dy(III) Coordination Polymer Material as a Dual-Functional Fluorescent Sensor for the Selective Detection of Inorganic Pollutants.

A Dy(III) coordination polymer (CP), [Dy(spasds)(H2O)2]n (1) (Na2Hspasds = 5-(4-sulfophenylazo)salicylic disodium salt), has been synthesized using a hydrothermal method and characterized. 1 features a 2D layered structure, where the spasda3- anions act as pentadentate ligands, adopting carboxylate, sulfonate and phenolate groups to bridge with four Dy centers in η3-μ1: μ2, η2-μ1: μ1, and monodentate coordination modes, respectively. It possesses a unique (4,4)-connected net with a Schläfli symbol of {44·62}{4}2. The luminescence study revealed that 1 exhibited a broad fluorescent emission band at 392 nm. Moreover, the visual blue color has been confirmed by the CIE plot. 1 can serve as a dual-functional luminescent sensor toward Fe3+ and MnO4- through the luminescence quenching effect, with limits of detection (LODs) of 9.30 × 10-7 and 1.19 × 10-6 M, respectively. The LODs are relatively low in comparison with those of the reported CP-based sensors for Fe3+ and MnO4-. In addition, 1 also has high selectivity and remarkable anti-interference ability, as well as good recyclability for at least five cycles. Furthermore, the potential application of the sensor for the detection of Fe3+ and MnO4- was studied through simulated wastewater samples with different concentrations. The possible sensing mechanisms were investigated using Ultraviolet-Visible (UV-Vis) absorption spectroscopy and density functional theory (DFT) calculations. The results revealed that the luminescence turn-off effects toward Fe3+ and MnO4- were caused by competitive absorption and photoinduced electron transfer (PET), and competitive absorption and inner filter effect (IFE), respectively.

Ratiometric Fluorescence Depending on In/Out Isomerism of Host‐Guest Conjugate Having a Fluorosolvatochromic Dye

Host‐guest conjugate is a promising strategy for providing outstanding molecules. Herein, we designed host‐guest conjugate HG1, which comprises a hydrophilic host unit, tetraaza[2.2.1.2.2.1]paracyclophane CPX2with a microhydrophobic cavity, and a guest unit, 2,3‐naphthalimide fused with two benzothiophenes G1 exhibiting fluorosolvatochromism, linked with an oxyethylene chain. HG1 initially showed a fluorescence band at 585 nm in MeOH/H2O (1/499 v/v); however, this band decreased with time, and instead, a new band at 430 nm appeared. The CIE chromaticity diagram showed that the fluorescent color changed from yellow‐orange to blue via white. NMR analysis of HG1 in methanol‐d4 exhibited different signals of the G1 unit between the blue and yellow fluorescent structures. The blue fluorescent structures showed asymmetrical signals assigned as the G1 unit, affected by the cavity environment of the CPX2 unit. Consequently, HG1 can form two conformations: In‐form and Out‐form. In In‐form, the G1 unit is inside the hydrophobic cavity of the CPX2 unit and shows blue fluorescence. In Out‐form, the G1 unit is outside the CPX2 unit and shows yellow fluorescence in an aqueous solvent. Therefore, HG1 performs as a ratiometric fluorophore depending on the in/out isomerism of the host‐guest conjugate.

Multifunctional cyanoaryl porphyrazine pigments with push-pull structure of macrocycle framing: Photophysics and possible applications

We report the experimental study of fluorescence properties of three porphyrazine derivatives, distinct in the number of fused aromatic rings in aryl groups contained in the macrocycle frame and/or presence of Pd in the macrocycle, in solutions with biological molecules and in methanol-glycerol mixtures. Spectral and lifetime fluorescence analysis has revealed that all three pigments demonstrated two fluorescence transition bands from the first S1 and the second S2 electronic excited states to the ground state S0, and thus followed the anti-Kasha’s rule. Strong dependence of the quantum yield and lifetimes in the S1 → S0 fluorescence band on solution viscosity was observed. A significant increase of the fluorescence decay times and fluorescence intensity with albumin concentration and with presence of other biological molecules in solution was observed as well. A model of the low-laying energy states of porphyrazine derivatives has been developed for elucidation of the fluorescence properties observed, that took into account several radiative and non-radiative relaxation channels in molecular excited states. In particular, the model suggests that the first electronic excited state consists of planar and bent conformations separated by a potential energy barrier and shows a typical molecular-rotor behavior as a function of solution viscosity. Potential applications of the porphyrazine pigments as viscosity sensors and fluorescence probes were considered.

Enhanced Quantum Efficiency of Near-IR Perovskite Light Emitting Diodes Via Dual Interfacial Modification

Near-infrared (NIR) light-emitting diodes play a crucial role in a wide range of applications, including sensors, night vision displays, security systems, medicine, spectroscopy, and military applications. The potential for high-performance NIR perovskite light-emitting diodes (NIR-PeLEDs) has been highlighted with the impressive advancement of fluorescent perovskite thin films. These PeLEDs exhibit promising features such as a tunable band gap, high color purity, and low non-radiative recombination rates. Despite these advantages, the current state-of-the-art NIR-PeLEDs faces challenges primarily related to poor film quality and increased defect states, leading to limitations in external quantum efficiency (EQE) and operational stability. In addressing these issues, we present a novel dual interfacial modification approach involving the incorporation of fluorinated phenethylammonium iodide (F-PEAI), a bulky organic cation, at both the bottom and top interfaces of perovskite emitting films. The modified interfaces result in perovskite films with a smoother surface morphology, complete coverage, and high crystallinity, leading to a red-shifted fluorescence band extending toward 800 nm. Furthermore, the introduction of F-PEAI facilitates the formation of compact and fine grains in perovskite films, contributing to an enhanced photoluminescence quantum yield (PLQY). Consequently, NIR-PeLEDs modified with F-PEAI demonstrate improved EQE values coupled with enhanced operational stability. The combination of electrical, optical, and physical analyses of both films and devices underscores the effectiveness of the dual interface modification in developing efficient NIR perovskite LEDs suitable for practical applications.

(Invited) Comprehensive Analysis of Exciton Diffusion with Time-Resolved Fluorescence Spectroscopy, Anisotropy and Imaging

Excitons produced in materials play a crucial role in photo-energy conversion such as photovoltaics and electroluminescence devices. The temporal and spatial diffusion of excitons is a key factor for dominating the fundamental performance of optoelectronic materials. In this context, analysis of the exciton diffusion dynamics is an important issue for obtaining the rational design of the materials. Excitons diffusing in materials can be characterized by several parameters such as the energy level, orientation of the transition dipole moment and spatial distribution, and the detection of these properties is required for the comprehensive analysis. In the present study, we show time-resolved fluorescence methods for detecting the above relevant properties of excitons.First, time-resolved fluorescence spectroscopy is a basic technique for analyzing the exciton diffusion dynamics. Fluorescence intensity is detected as functions of observation wavelength and time, and the spectral intensity and shift of fluorescence bands provide information on the population of excitons and their energy level. For example, dynamic Stokes shift indicates downhill energy migration and excitons are trapped by the defective site in molecular aggregates. Second, fluorescence anisotropy can be a good indicator for tracking the exciton diffusion in amorphous materials. Fluorescence anisotropy is sensitive to orientation change in transition dipole moments (TDMs) between absorption and fluorescence. In systems where the relative orientation of adjacent molecules is different from each other, such as amorphous solids, the exciton diffusion is accompanied with the change in TDM. Thus, appropriate modeling of molecular alignment enables quantitative estimation of the exciton diffusion coefficient and diffusion length from the anisotropy signal. Finally, time-resolved imaging is a combination of time-resolved spectroscopy and super-resolution microscopy, and an emergent technique for visualizing real-space propagation of excitons in materials. The diffraction-limited excitation beam produces excitons in several hundreds of nanometers and the subsequent exciton diffusion is evaluated by the spatial width of the fluorescence spot. The temporal broadening of the fluorescence spot directly reflects the exciton distribution and we can intuitively obtain the diffusion coefficient and length. Unlike the conventional methods for bulk materials, the advantage of the time-resolved imaging is the applicability to materials with nano- and meso-scale heterogeneous structure and it enables site-selective evaluation of the exciton transport capability. In the conference site, we will also show the application of the above methods to supramolecular polymers and thermally activated delayed fluorescence materials. Figure 1

Theoretical Study on Optoelectronic Properties of 1,4-Dithiazole-5,10-dihydrophenazine and Its B ← N-Fused Derivatives.

Recently, Liu et al. reported 1,4-dithiazole-5,10-dihydrophenazine (DTDHP) and its B ← N-fused derivative (DTHDHP-BF2), which were expected to show excellent optoelectronic properties (Angew. Chem. Int. Ed. 2022, 61, e202205893). However, their charge-transport performance and luminescence emission mechanisms have not been revealed. In this work, we used density functional theory (DFT) calculations to investigate the optoelectronic properties of DTDHP and DTHDHP-BF2 and analyzed the influence of the introduction of -BF2 on the basic parameters governing charge transport and injection in detail. Our calculation results showed that adding -BF2 could stabilize the frontier molecular orbitals and decrease the reorganization energies associated with electron transport due to the formation of B ← N bonds, and the intermolecular electronic couplings are greatly enhanced owing to the strong intermolecular F···H interactions. Based on the master equation coupled with the Marcus-Hush electron transfer theory, we theoretically predicted the charge transport properties of DTDHP and DTHDHP-BF2. The optimum hole mobility (3.87 cm2 V-1 S-1) and electron mobility (1.52 cm2 V-1 S-1) of DTHDHP-BF2 are, respectively, 3 and 9 times as high as the corresponding optimum values of compound DTDHP. Moreover, the assignments of multiple fluorescence bands in the experiment were confirmed by time-dependent density functional theory (TDDFT) calculations. The simulated emission spectra indicate that the experimental fluorescence maxima at 687 nm originates from the S1 → S0 transition of the double proton transfer phototautomer (T2H) of DTDHP, and the shoulder peak at ∼660 nm may be related to the excited-state single-proton transfer phototautomer (T1H); for DTHDHP-BF2, the experimental fluorescence maxima at 687 nm should be attributed to normal Stokes shifted emission, and the shifted fluorescence with a peak at 751 nm originates from the emission of the photodissociation product of DTHDHP-BF2.

Fluorescent Nanowires from Dual‐State Emitting Fluorophores Directed by Molecular Motors and Aggregation‐Induced Emission: Produce Quantized Light Spectrum

AbstractLuminescent materials require systems that exhibit both dual‐state emission (DSE) and aggregation‐induced emission (AIE) to overcome the limitation of aggregation‐caused quenching (ACQ). Herein, a molecular assembler capable of crafting nanowires that exhibit programmable fluorescence across a broad spectrum of colors in a precisely quantized manner is reported. Because it is a starburst dendritic box made of PAMAM dendrimer (P), controller (C) molecules, and motor (M) molecules, the assembler is called PCM. Here, Nile red is chosen as C and placed into the hollow core of the dendrimer; a double ratchet motor (DRM) is chosen as M and is connected to the N‐terminals of the PAMAM dendrimer. While aqueous dispersed PCM assemblers have broad fluorescence bands beyond 300 nm, their crafted nanowires produce quantized cyan‐green, yellow, and orange‐red light emission in the spectra. These PCM assemblers are shown to hold long‐term memory, rapid switching, and energy harvesting by modulating photonic bandgaps, causing a longer redshift in the solid phase. The DSE of PCM can yield versatile photonics applications like bioimaging and energy harvesting. As PCM nanowires can modulate photonic bandgaps to cause a longer redshift, PCM fluorophores hold promise for drug delivery and cell separation like infrared‐sensitive operations.

Karyotype diversity and genome size in the Cyphomandra clade of Solanum L. (Solanaceae)

Abstract The Cyphomandra clade, a distinct group within the Solanum L. genus, is characterized by remarkable traits, including large chromosomes and big genome sizes. We aimed to investigate whether these features are conserved within the Cyphomandra clade and how they differentiate this group from other Solanum species. We elaborated karyotypes based on CMA/DAPI banding and rDNA fluorescence in situ hybridization (FISH) and estimated the genome size from 12 species, eight belonging to Cyphomandra and four from related clades. All species showed metacentric or submetacentric chromosomes and symmetrical karyotypes, with 2n = 24, except S. mammosum L. (2n = 22). CMA/DAPI banding in combination with rDNA FISH revealed three distinct patterns of heterochromatin distribution (number and position of bands, all CMA+). Most species showed one pair of 35S and 5S rDNA on different chromosomes, except S. mammosum (one of the two pairs was observed in the same chromosome). Notable, the Cyphomandra clade species showed larger chromosomes and genome sizes than other species of Solanum, corroborating that these karyotype attributes are valuable to characterize the clade. The number of CMA/DAPI bands and rDNA sites does not justify the differences in the genome size. Therefore, the accumulation and dispersion of other repetitive sequences, like transposable elements, may be associated with the karyotype changes.

Introducing a π‐Skeleton Perpendicular to the Central Methylene Carbon in Alkanediamides: Design of Supramolecular Polymers with an Offset π‐Stacking Arrangement

AbstractThe self‐assembly behavior of a heptanediamide derivative that contains a four‐ring fused π‐skeleton on its central methylene carbon atom has been examined. This molecule, which also contains two octyl chains, gelated the nonpolar solvent methylcyclohexane through the formation of fibrous nanostructures with hydrogen‐bonding networks through a cooperative nucleation–elongation process. The supramolecular polymerization is accompanied by bathochromic shifts of both the absorption and fluorescence bands while maintaining a fluorescence quantum yield comparable to that of the monomeric state. Theoretical calculations provided an energetically stable structure, in which the π‐skeletons are stacked with an offset of more than 8.0 Å, replicating the experimentally observed absorption change due to exciton coupling. Moreover, a slow transition with an inversion of the chiral arrangement of the π‐conjugated moieties was induced by replacing the octyl chains with chiral alkyl chains. Our molecular‐design strategy was further applied to a five‐ring fused π‐skeleton, which also forms an offset π‐stacking arrangement and exhibits more effective chiral exciton coupling in the aggregated state.

Introducing a π-Skeleton Perpendicular to the Central Methylene Carbon in Alkanediamides: Design of Supramolecular Polymers with an Offset π-Stacking Arrangement.

The self-assembly behavior of a heptanediamide derivative that contains a four-ring fused π-skeleton on its central methylene carbon atom has been examined. This molecule, which also contains two octyl chains, gelated the nonpolar solvent methylcyclohexane through the formation of fibrous nanostructures with hydrogen-bonding networks through a cooperative nucleation-elongation process. The supramolecular polymerization is accompanied by bathochromic shifts of both the absorption and fluorescence bands while maintaining a fluorescence quantum yield comparable to that of the monomeric state. Theoretical calculations provided an energetically stable structure, in which the π-skeletons are stacked with an offset of more than 8.0 Å, replicating the experimentally observed absorption change due to exciton coupling. Moreover, a slow transition with an inversion of the chiral arrangement of the π-conjugated moieties was induced by replacing the octyl chains with chiral alkyl chains. Our molecular-design strategy was further applied to a five-ring fused π-skeleton, which also forms an offset π-stacking arrangement and exhibits more effective chiral exciton coupling in the aggregated state.