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We demonstrate directed translocation of ClO4− anions from cationic to neutral binding site along the synthetized BPym‐OH dye molecule that exhibits coupled excited‐state intramolecular proton‐transfer (ESIPT) and charge‐transfer (CT) reaction (PCCT). The results of steady‐state and time‐resolved spectroscopy together with computer simulation and modeling show that in low polar toluene the excited‐state redistribution of electronic charge enhanced by ESIPT generates the driving force, which is much stronger than by CT reaction itself and provides more informative gigantic shifts of fluorescence spectra signaling on ultrafast ion motion. The associated with ion translocation red‐shifted fluorescence band (at 750 nm, extending to near‐IR region) appears at the time ~83 ps as a result of electrochromic modulation of PCCT reaction. It occurs at substantial delay to PCCT that displayed fluorescence band at 640 nm and risetime of <200 fs. Thus, it becomes possible to visualize the manifestations of light‐triggered ion translocation and of its driving force by fluorescence techniques and to separate them in time and energy domains. [ABSTRACT FROM AUTHOR]

We demonstrate directed translocation of ClO4− anions from cationic to neutral binding site along the synthetized BPym‐OH dye molecule that exhibits coupled excited‐state intramolecular proton‐transfer (ESIPT) and charge‐transfer (CT) reaction (PCCT). The results of steady‐state and time‐resolved spectroscopy together with computer simulation and modeling show that in low polar toluene the excited‐state redistribution of electronic charge enhanced by ESIPT generates the driving force, which is much stronger than by CT reaction itself and provides more informative gigantic shifts of fluorescence spectra signaling on ultrafast ion motion. The associated with ion translocation red‐shifted fluorescence band (at 750 nm, extending to near‐IR region) appears at the time ~83 ps as a result of electrochromic modulation of PCCT reaction. It occurs at substantial delay to PCCT that displayed fluorescence band at 640 nm and risetime of <200 fs. Thus, it becomes possible to visualize the manifestations of light‐triggered ion translocation and of its driving force by fluorescence techniques and to separate them in time and energy domains. [ABSTRACT FROM AUTHOR]

We propose a new concept exploiting thermally activated delayed fluorescence (TADF) molecules as photosensitizers, storage units and signal transducers to harness solar thermal energy. Molecular composites based on the TADF core phenoxazine–triphenyltriazine (PXZ-TRZ) anchored with norbornadiene (NBD) were synthesized, yielding compounds PZDN and PZTN with two and four NBD units, respectively. Upon visible-light excitation, energy transfer to the triplet state of NBD occurred, followed by NBD → quadricyclane (QC) conversion, which can be monitored by changes in steady-state or time-resolved spectra. The small S1-T1 energy gap was found to be advantageous in optimizing the solar excitation wavelength. Upon tuning the molecule's triplet state energy lower than that of NBD (61 kcal/mol), as achieved by another composite PZQN, the efficiency of the NBD → QC conversion decreased drastically. Upon catalysis, the reverse QC → NBD reaction occurred at room temperature, converting the stored chemical energy back to heat with excellent reversibility. Direct conversion of solar energy to stored chemical energy can be achieved through photoisomerization. Here, authors exploit thermally activated delayed fluorescence materials as a photosensitizer and signal transducer to harness solar energy, to maximize solar spectrum harvesting without sacrificing energy storage time. [ABSTRACT FROM AUTHOR]

We propose a new concept exploiting thermally activated delayed fluorescence (TADF) molecules as photosensitizers, storage units and signal transducers to harness solar thermal energy. Molecular composites based on the TADF core phenoxazine–triphenyltriazine (PXZ-TRZ) anchored with norbornadiene (NBD) were synthesized, yielding compounds PZDN and PZTN with two and four NBD units, respectively. Upon visible-light excitation, energy transfer to the triplet state of NBD occurred, followed by NBD → quadricyclane (QC) conversion, which can be monitored by changes in steady-state or time-resolved spectra. The small S1-T1 energy gap was found to be advantageous in optimizing the solar excitation wavelength. Upon tuning the molecule's triplet state energy lower than that of NBD (61 kcal/mol), as achieved by another composite PZQN, the efficiency of the NBD → QC conversion decreased drastically. Upon catalysis, the reverse QC → NBD reaction occurred at room temperature, converting the stored chemical energy back to heat with excellent reversibility. Direct conversion of solar energy to stored chemical energy can be achieved through photoisomerization. Here, authors exploit thermally activated delayed fluorescence materials as a photosensitizer and signal transducer to harness solar energy, to maximize solar spectrum harvesting without sacrificing energy storage time. [ABSTRACT FROM AUTHOR]

A series of new six (anilido)‐five (thiazole) membered ring boron difluoride dyes, namely BFs, have been synthesized from the corresponding para‐ and meta‐substituted 2‐(2'‐methylaminophenyl) benzothiazoles through complexation with boron trifluoride. Depending on the substituent effect, the derivatives can switch the emission properties from fluorescence with 100 % emission yield to slim fluorescence but >90 % triplet state population and peak wavelength tuning from 490 nm to 610 nm. Compared with non‐complexed precursors, the rigid, highly planar structure and significantly red‐shifted absorption and emission for BFs indicate that the boron center facilitates the formation of a bridge leading to increased rigidity, and is also involved in π‐conjugation, increasing the transition dipole and suppressing the non‐radiative internal conversion. Together with optical ∼100 % transparent window around 325–375 nm, BFs may find unique applications, among which the fluorescence up‐conversion via triplet‐triplet annihilation is demonstrated. [ABSTRACT FROM AUTHOR]

The encapsulation and/or surface modification can stabilize and protect the phosphorescence bio‐probes but impede their intravenous delivery across biological barriers. Here, a new class of biocompatible rhenium (ReI) diimine carbonyl complexes is developed, which can efficaciously permeate normal vessel walls and then functionalize the extravascular collagen matrixes as in situ oxygen sensor. Without protective agents, ReI‐diimine complex already exhibits excellent emission yield (34%, λem = 583 nm) and large two‐photon absorption cross‐sections (σ2 = 300 GM @ 800 nm) in water (pH 7.4). After extravasation, remarkably, the collagen‐bound probes further enhanced their excitation efficiency by increasing the deoxygenated lifetime from 4.0 to 7.5 µs, paving a way to visualize tumor hypoxia and tissue ischemia in vivo. The post‐extravasation functionalization of extracellular matrixes demonstrates a new methodology for biomaterial‐empowered phosphorescence sensing and imaging. [ABSTRACT FROM AUTHOR]

6‐Cyano‐7‐aminoquinoline (6CN−7AQ) and 3‐cyano‐7‐aminoquinoline (3CN−7AQ) were synthesized and found to exhibit intense emission with quantum yield as high as 63 % and 85 %, respectively, in water. Conversely, their derivatives 6‐cyano‐7‐azidoquinoline (6CN−7N3Q) and 3‐cyano‐7‐azidoquinoline (3CN−7N3Q) show virtually no emission, which makes them suitable to be used as recognition agents in azide reactions based on fluorescence recovery. Moreover, conjugation of 6CN−7AQ with a hydrophobic biomembrane‐penetration peptide PFVYLI renders a nearly non‐emissive 6CN−7AQ‐PFVYLI composite, which can be digested by proteinase K, recovering the highly emissive 6CN−7AQ with ∼200‐fold enhancement. The result provides an effective early confirmation for RT‐qPCR in viral detection. [ABSTRACT FROM AUTHOR]

Finding a relationship between kinetics and thermodynamics may be difficult. However, semi‐empirical rules exist to compensate for this shortcoming, among which the Bell–Evans–Polanyi (B‐E‐P) principle is an example for reactions involving bond breakage and reformation. We expand the B‐E‐P principle to a new territory by probing photoinduced structure planarization (PISP) of a series of dibenz[b,f]azepine derivatives incorporating bent‐to‐planar and rotation motion. The latter involves twisting of the partial double bond character, thereby inducing a barrier that is substituent dependent at the para N‐phenyl position. The transition‐state structure and frequency data satisfy and broaden the B‐E‐P principle to PISP reactions without bond rearrangement. Together with dual emissions during PISP, this makes possible harnessing of the kinetics/thermodynamics relationship and hence ratiometric luminescence properties for excited‐state structural transformations. [ABSTRACT FROM AUTHOR]

Finding a relationship between kinetics and thermodynamics may be difficult. However, semi‐empirical rules exist to compensate for this shortcoming, among which the Bell–Evans–Polanyi (B‐E‐P) principle is an example for reactions involving bond breakage and reformation. We expand the B‐E‐P principle to a new territory by probing photoinduced structure planarization (PISP) of a series of dibenz[b,f]azepine derivatives incorporating bent‐to‐planar and rotation motion. The latter involves twisting of the partial double bond character, thereby inducing a barrier that is substituent dependent at the para N‐phenyl position. The transition‐state structure and frequency data satisfy and broaden the B‐E‐P principle to PISP reactions without bond rearrangement. Together with dual emissions during PISP, this makes possible harnessing of the kinetics/thermodynamics relationship and hence ratiometric luminescence properties for excited‐state structural transformations. [ABSTRACT FROM AUTHOR]

The development of high-performance near-infrared organic light-emitting diodes is hindered by strong non-radiative processes as governed by the energy gap law. Here, we show that exciton delocalization, which serves to decouple the exciton band from highly vibrational ladders in the S0 ground state, can bring substantial enhancements in the photoluminescence quantum yield of emitters, bypassing the energy gap law. Experimental proof is provided by the design and synthesis of a series of new Pt(ii) complexes with a delocalization length of 5–9 molecules that emit at 866–960 nm with a photoluminescence quantum yield of 5–12% in solid films. The corresponding near-infrared organic light-emitting diodes emit light with a 930 nm peak wavelength and a high external quantum efficiency up to 2.14% and a radiance of 41.6 W sr−1 m−2. Both theoretical and experimental results confirm the exciton–vibration decoupling strategy, which should be broadly applicable to other well-aligned molecular solids. Pt(ii) complexes allow the fabrication of efficient near-infrared organic light-emitting diodes that operate beyond the 900 nm region. [ABSTRACT FROM AUTHOR]

Monolayer transition‐metal dichalcogenides have inspired worldwide efforts in optoelectronic devices but real applications are hindered with their reduced optical absorption due to their atomically ultrathin signature. In this study, by utilizing their biradical nature such as excellent absorption coefficient, broad bandwidth from the ultraviolet to near‐infrared region, and small triplet–singlet energy gap, a series of helicene 5,14‐diaryldiindeno[2,1‐f:1′,2′‐j]picene (DDP) derivatives (1ab, 1ac, and 1bb) are integrated with monolayer MoS2 for extraordinary photodetector performance and outstanding stability. Via comprehensive time‐resolved studies, the interfacial charge‐transfer process from the DDPs to the MoS2 layer is evidenced by the stabilized exciton property of the organics (1ac)/MoS2 heterostructure. Significantly, the 1ac/MoS2 photodetector exhibits an ultrahigh photoresponsivity of 5 × 107 A W−1 and a fast response speed of 45 ms due to the highly efficient photoexcited carrier separation and the matched type‐II energy band alignment. The biradical 1ac/MoS2 hybrid photodetector shows no sign of degradation after one‐month operation. The results pave a new avenue for biradical based high‐performance and super‐broadband optoelectronic devices. [ABSTRACT FROM AUTHOR]

With the aim of generalizing the structure–properties relationship of bending heterocyclic molecules that undergo prominent photoinduced structural planarization (PISP), a series of new dihydrodibenzo[ac]phenazine derivatives in which one nitrogen atom is replaced by oxygen (PNO), sulfur (PNS), selenium (PNSe), or dimethylmethanediyl (PNC) was strategically designed and synthesized. Compounds PNO, PNS, and PNSe have significantly nonplanar geometries in the ground state, which undergo PISP to give a planarlike conformer and hence a large emission Stokes shift. A combination of femtosecond early relaxation dynamics and computational approaches established an R*→I* (intermediate)→P* sequential kinetic pattern for PNS and PNSe, whereas PNO undergoes R*→P* one‐step kinetics. The polarization ability of the substituted heteroatoms, which is in the order O

7‐Aminoquinoline (7AQ) and various amino derivatives thereof (‐NHR) have been strategically designed and synthesized to study their excited‐state proton‐transfer (ESPT) properties. Due to the large separation between the proton donor ‐NHR and the acceptor ‐N‐ site, ESPT in 7AQ derivatives, if available, should proceed under protic solvent catalysis. ESPT is found to be influenced by the acidity of ‐NHR and the basicity of the proton‐acceptor ‐N‐ in the quinoline moiety. The latter is varied by the resonance effect at the quinoline ‐N‐ site induced by the ‐NHR substituent. For those 7AQ derivatives undergoing ESPT, increased quinoline basicity results in a faster rate of ESPT, implying that proton donation from methanol to the quinoline moiety may serve as a key step in the process. Our studies also indicate the existence of an equilibrium between cis and trans arrangements of ‐NHR in terms of its hydrogen‐bond (H‐bond) configuration with methanol, whereby only the cis‐H‐bonded form undergoes methanol‐assisted ESPT. With one exception, the interconversion between cis and trans configurations is much faster than the rate of ESPT, yielding amino‐type (normal form) and imine‐type (proton‐transfer tautomer) emissions with distinct relaxation dynamics. [ABSTRACT FROM AUTHOR]

Indeno[1,2‐b]fluorene‐based [2,2]cyclophanes with 4n/4n and 4n/[4n+2] π‐electron systems were prepared, and their structures were identified by X‐ray crystallography. With short π–π distances around 3.0 Å, [2.2](5,11)indeno[1,2‐b]fluorenophane and its precursor [2.2](5,11)indeno[1,2‐b]fluorene‐6,12‐dionophane exhibit remarkable transannular interactions, leading to their unusual electrochemical and photophysical properties. With the aid of femtosecond transient absorption spectroscopy, the transition from the monomeric excited state to the redshifted H‐type dimeric state was first observed, correlating to the calculated excitonic energy splitting and the steady‐state absorption spectra induced by charge‐transfer‐mediated superexchange interaction. [ABSTRACT FROM AUTHOR]

Indeno[1,2‐b]fluorene‐based [2,2]cyclophanes with 4n/4n and 4n/[4n+2] π‐electron systems were prepared, and their structures were identified by X‐ray crystallography. With short π–π distances around 3.0 Å, [2.2](5,11)indeno[1,2‐b]fluorenophane and its precursor [2.2](5,11)indeno[1,2‐b]fluorene‐6,12‐dionophane exhibit remarkable transannular interactions, leading to their unusual electrochemical and photophysical properties. With the aid of femtosecond transient absorption spectroscopy, the transition from the monomeric excited state to the redshifted H‐type dimeric state was first observed, correlating to the calculated excitonic energy splitting and the steady‐state absorption spectra induced by charge‐transfer‐mediated superexchange interaction. [ABSTRACT FROM AUTHOR]

Diindeno‐fused dibenzo[a,h]anthracene 6 and diindeno‐fused dibenzo[c,l]chrysene 9 contain the key moieties 1,4‐quinodipropene (1,4‐QDP) and 2,6‐naphthoquinodipropene (2,6‐NQDP), respectively, and they both have an open‐shell singlet ground state. The latter compound exhibits a strong biradical character and interesting properties, including a low ΔET−S (2.44 kcal mol−1), a small HOMO–LUMO gap (1.06 eV), a wide photoabsorption range (250–1172 nm), and a large two‐photon absorption cross‐section (σ=1342±56 GM). This work verifies that 6 has a slightly larger HOMO–LUMO gap and ΔET−S than its helical isomer diindeno[2,1‐f:1′,2′‐j]picene (DIP), but is a much stronger two‐photon absorber, verifying the important effect of geometry on the photophysical properties. [ABSTRACT FROM AUTHOR]

Regulatory regions harbor multiple transcription factor (TF) recognition sites; however, the contribution of individual sites to regulatory function remains challenging to define. We describe an approach that exploits the error-prone nature of genome editing-induced double-strand break repair to map functional elements within regulatory DNA at nucleotide resolution. We demonstrate the approach on a human erythroid enhancer, revealing single TF recognition sites that gate the majority of downstream regulatory function. [ABSTRACT FROM AUTHOR]

Human embryonic stem cells provide an alternative to using human embryos for studying developmentally regulated gene expression. The co-expression of high levels of embryonic ε and fetal γ globin by the hESC-derived erythroblasts allows the interrogation of ε globin regulation at the transcriptional and epigenetic level which could only be attained previously by studying cell lines or transgenic mice. In this study, we compared the histone modifications across the β globin locus of the undifferentiated hESCs and hESC-, FL-, and mobilized PB CD34 cells-derived erythroblasts, which have distinct globin expression patterns corresponding to their developmental stages. We demonstrated that the histone codes employed by the β globin locus are conserved throughout development. Furthermore, in spite of the close proximity of the ε globin promoter, as compared to the β or γ globin promoter, with the LCR, a chromatin loop was also formed between the LCR and the active ε globin promoter, similar to the loop that forms between the β or γ globin promoters and the LCR, in contrary to the previously proposed tracking mechanism. [ABSTRACT FROM AUTHOR]

Severe anemia is a major life-threatening complication of malaria. The roles of erythropoietin (Epo) and erythropoiesis during blood-stage malaria were investigated. By treating Plasmodium chabaudi AS--infected C57BL/6 (B6) mice, which are resistant to malaria, with polyclonal anti--human Epo neutralizing antibody, we demonstrated that Epo-induced reticulocytosis was important for alleviating malarial anemia and for host survival. By inducing erythropoiesis in A/J mice, which are susceptible to malaria, and in B6 mice at various periods during infection, by use of exogenous recombinant murine Epo, untimely onset of reticulocytosis was shown to augment multiplication of parasites and result in lethal infection. However, timely inducement of reticulocytosis with Epo treatment alleviated malarial anemia and increased survival. Our data reveal the important role of Epo-induced reticulocytosis in modulating the course and outcome of blood-stage malaria. However, the mechanisms underlying the increased mortality associated with untimely treatment with Epo and the increased protection associated with timely treatment with Epo remain to be investigated. [ABSTRACT FROM AUTHOR]