Large Dipole Moment Research Articles

Modeling, simulation and experimental validation of solid media in capacitive wireless power transfer

Capacitive wireless power transfer (CPT) employs an electric field to transmit energy through a medium. Air is the most often used and a well-understood medium. However, CPT can also bridge other solid media and even benefit from them as the dielectric properties of the medium govern the strength of the capacitive coupling. The parasitic elements of the coupling are influenced by the medium, in particular the leakage resistance. In this work, an analytical model is proposed that quantifies the leakage resistance losses in CPT systems for media. The model is validated by both finite element simulations and experiments on three different media: air, plexiglass and polytetrafluorideethylene (PTFE). As a result, at 1 MHz, the leakage resistance of plexiglass is 6 times higher than that of air while that of PTFE is 1.7 times smaller. This proves that a material with a large dipole moment generates larger losses in the medium which negatively affect system efficiency.

The influence of molecular shape and electronic properties on the formation of the ferroelectric nematic phase

ABSTRACT The synthesis and characterisation of two series of ferroelectric nematogens based on RM734 having an additional methoxy group on the central phenyl ring are reported, the 3-methoxy-4-((4-nitrophenoxy)carbonyl)phenyl 2-alkoxy-4-alkoxybenzoates (7-m-n) and the 3-methoxy-4-((3-fluoro-4-nitrophenoxy)carbonyl)phenyl 2-alkoxy-4-alkoxybenzoates (8-m-n). In order to compare the behaviour of these series to those of the corresponding materials that do not contain the methoxy group on the central phenyl ring, we also report the synthesis and characterisation of 4-[(4-nitrophenoxy)carbonyl]phenyl 4-methoxybenzoate (11-0-1), 4-[(3-fluoro-4-nitrophenoxy)carbonyl]phenyl 4-methoxybenzoate (12-0-1) and 4-[(3-fluoro-4-nitrophenoxy)carbonyl]phenyl 2,4-diethoxybenzoate (12-2-2). Two compounds in which a lateral ethoxy chain is attached to the central ring, 3-ethoxy-4-[(4-nitrophenoxy)carbonyl]phenyl 2,4-dimethoxybenzoate (18-2-1) and 3-ethoxy-4-[(3-fluoro-4-nitrophenoxy)carbonyl]phenyl 2,4-dimethoxybenzoate (19-2-1), are also described. The behaviour of these materials shows that the relative stabilities of the ferroelectric nematic, NF, and conventional nematic, N, phases are governed by a subtle interplay of steric and electronic factors. Furthermore, the electronic factors are better understood in terms of isolated regions of electron density rather than by a single large longitudinal dipole moment. In terms of molecular shape, to observe the NF phase it appears that the molecular structure must include one or more lateral substituents that enhance molecular biaxiality and destabilise the N phase.

Modulating the Dipole Moment of Secondary Ammonium Spacers for Efficient 2D Ruddlesden-Popper Perovskite Solar Cells.

Layered two-dimensional (2D) perovskites are emerging as promising optoelectronic materials owing to their excellent environmental stability. Regulating the dipole moment of organic spacers has the potential to reduce the exciton binding energy (Eb ) of 2D perovskites and improve their photovoltaic performance. Here, we developed two azetidine-based secondary ammonium spacers with different electron-withdrawing groups, namely 3-hydroxyazatidine (3-OHAz) and 3,3-difluoroazetidine (3,3-DFAz) spacers, for 2D Ruddlesden-Popper (RP) perovskites. It was found that the large dipole moment of the fluorinated dipole spacer could effectively enhance the interaction between organic spacers and inorganic layers, leading to improved charge dissociation in 2D RP perovskite. In contrast to 3-OHAz spacer, the 2D perovskite using 3,3-DFAz as spacer also shows improved film quality, optimized energy level alignment, and reduced exciton binding energy. As a result, the 2D perovskite (n=4) device based on 3,3-DFAz yields an outstanding efficiency of 19.28 %, surpassing that of the 3-OHAz-Pb device (PCE=11.35 %). The efficiency was further improved to 19.85 % when using mixed A-site cation of MA0.95 FA0.05 . This work provides an effective strategy for modulating the energy level alignment and reducing the Eb by regulating the dipole moment of organic spacers, ultimately enabling the development of high-performance 2D perovskite solar cells.

Modulating the Dipole Moment of Secondary Ammonium Spacers for Efficient 2D Ruddlesden‐Popper Perovskite Solar Cells

AbstractLayered two‐dimensional (2D) perovskites are emerging as promising optoelectronic materials owing to their excellent environmental stability. Regulating the dipole moment of organic spacers has the potential to reduce the exciton binding energy (Eb) of 2D perovskites and improve their photovoltaic performance. Here, we developed two azetidine‐based secondary ammonium spacers with different electron‐withdrawing groups, namely 3‐hydroxyazatidine (3‐OHAz) and 3,3‐difluoroazetidine (3,3‐DFAz) spacers, for 2D Ruddlesden‐Popper (RP) perovskites. It was found that the large dipole moment of the fluorinated dipole spacer could effectively enhance the interaction between organic spacers and inorganic layers, leading to improved charge dissociation in 2D RP perovskite. In contrast to 3‐OHAz spacer, the 2D perovskite using 3,3‐DFAz as spacer also shows improved film quality, optimized energy level alignment, and reduced exciton binding energy. As a result, the 2D perovskite (n=4) device based on 3,3‐DFAz yields an outstanding efficiency of 19.28 %, surpassing that of the 3‐OHAz‐Pb device (PCE=11.35 %). The efficiency was further improved to 19.85 % when using mixed A‐site cation of MA0.95FA0.05. This work provides an effective strategy for modulating the energy level alignment and reducing the Eb by regulating the dipole moment of organic spacers, ultimately enabling the development of high‐performance 2D perovskite solar cells.

A DFT study on photodissociation of the palladium tetrachloride anion PdCl42− in solution

Photodissociation of PdCl42− in water is investigated using the time-dependent DFT method with the polarized continuum model. First, to find out the exchange–correlation functional that can well describe the present system we make following two comparisons using many functionals: (i) the DFT absorption spectrum vs. experiment; (ii) the DFT one-dimensional (1D) potential energy curves (PECs) vs. the previous MRCI 1D PECs. As a result of comparison, it is found that the range-separated hybrid functionals well reproduce the observed spectrum and, among these, the M11 functional may be the most reasonable choice. Next, using M11, we calculate ground and excited-state 1D PECs for single Cl loss in water and the ground-state two-dimensional (2D) potential energy surface (PES) for double Cl loss in water. It is revealed in the 1D PECs in water that electronic excitations to the PECs that have large transition dipole moments with the ground electronic state may easily lead to the PdCl3− + Cl− dissociation channel, which is similar to single Cl loss in the gas phase. It is also found that the ground-state 2D PES in water correlates with the PdCl2 + 2Cl− dissociation channel with no transition state on the way to it. This is different from the prediction in the gas phase; the ground-state 2D PES correlates with the PdCl2 + Cl2− dissociation channel with a transition state on the minimum energy path leading to it.

Donor-acceptor pairs in wide-bandgap semiconductors for quantum technology applications

We propose a quantum science platform utilizing the dipole-dipole coupling between donor-acceptor pairs (DAPs) in wide bandgap semiconductors to realize optically controllable, long-range interactions between defects in the solid state. We carry out calculations based on density functional theory (DFT) to investigate the electronic structure and interactions of DAPs formed by various substitutional point-defects in diamond and silicon carbide (SiC). We determine the most stable charge states and evaluate zero phonon lines using constrained DFT and compare our results with those of simple donor-acceptor pair (DAP) models. We show that polarization differences between ground and excited states lead to unusually large electric dipole moments for several DAPs in diamond and SiC. We predict photoluminescence spectra for selected substitutional atoms and show that while B-N pairs in diamond are challenging to control due to their large electron-phonon coupling, DAPs in SiC, especially Al-N pairs, are suitable candidates to realize long-range optically controllable interactions.

Helicene‐type β‐isoindigo‐based boron‐dipyrromethene analogs with strong near‐infrared chiroptical activity

AbstractNear‐infrared (NIR) chiroptical response has been less explored because it is challenging to achieve both chirality and NIR absorption/emission. Herein, we describe the design of heterohelicene‐type β‐isoindigo‐based boron‐dipyrromethene (BODIPY) analogs (β‐IBs), which shift the absorption peak to 800 nm and produce significant Cotton effects (127.8 M−1 cm−1) and absorbance dissymmetry factors (|gabs| = 3.5 × 10−3). The luminescence dissymmetry factor (glum) and circularly polarized luminescence (CPL) brightness (BCPL) of up to 1.24 × 10−3 and 1.78 M−1 cm−1 were realized beyond 800 nm. These β‐IBs are the first examples of helicene‐type compounds with the highest gabs in the NIR region and CPL beyond 800 nm. Theoretical calculations demonstrate that the strong chiroptical activities are triggered by their large transition magnetic dipole moments. This study not only provides a new approach to the synthesis of a larger variety of unprecedented helicene‐type BODIPY analogs but also demonstrates excellent NIR chiroptical properties.

Enhanced optoelectronic properties with aromatic bridges: A computational study on N‐methyl pyridinium and phenolate types of push‐pull zwitterions

AbstractA series of zwitterions with varying bridges, connecting N‐methyl pyridinium acceptor, with phenolate donor, are investigated using various methodologies like, HF, B3LYP, CAM‐B3LYP and ωB97xD. In this systematic study effects of various mono aromatic rings as bridges, on the response properties like, the dipole moments (μ), polarizabilities (α), hyperpolarizabilities (β) and adiabatic absorptions were analyzed using CPHF and TDDFT (or TDHF) theories. Compared to many traditional bridges, as well as without a bridge, enhanced nonlinear optical (2ND order NLO) responses were observed for these aromatically bridged zwitterions (with benzene ring as bridge ~5.3 times and ~7.9 times enhanced hyperpolarizabilities were observed compared to either the ethylene bridge or without any bridge cases, respectively). Also, many significant differences and large enhancements in response properties were observed compared to our earlier works on non‐zwitterionic system (~4.3 times enhanced hyperpolarizability—benzene as bridge case). For some bridge cases, 10‐ to 15‐fold enhanced hyperpolarizabilities were observed compared to without any bridge case. This work reports a class of non‐TICT chromophores, promoting bridge aromaticity control on structure–property correlation, as a suitable and efficient chromophore design strategy to create a wide range of function molecular chromophores. Also, unidirectional natures of response properties and large dipole moments can make these zwitterions suitable 1D‐molecular materials for various contemporary technological applications, as poled polymer‐based materials.

High Open‐Circuit Voltage (1.197 V) in Large‐Area (1 cm2) Inverted Perovskite Solar Cell via Interface Planarization and Highly Polar Self‐Assembled Monolayer

AbstractThe efficiency loss caused by area scaling is one of the key factors hindering the industrial development of perovskite solar cells. The energy loss and contact issues in the buried interface are the main reasons. Here, a new self‐assembled monolayer (SAM), Ph‐4PACz, with a large dipole moment (2.32 D) is obtained . It is found that Ph‐4PACz with high polarity can improve the band alignment and minimize the energy loss , resulting in an open‐circuit voltage (Voc) as high as 1.2 V for 1.55 eV perovskite. However, when applied to large‐area devices, the fill factor (FF) still suffered from significant attenuation. Therefore, alumina nanoparticles (Al2O3‐NPs) are introduced to the interface between Ph‐4PACz and rough FTO substrate to further improve the flatness , resulting in a conformal perovskite film with almost no voids in the buried interface, thus promoting low exciton binding energy, fast hot‐carrier extraction and low non‐radiative recombination. The final devices achieved a small‐area power conversion efficiency (PCE) of 25.60% and a large‐area (1 cm2) PCE of 24.61% (certified at 24.48%), which represents one of the highest PCE for single device ≥ 1 cm2 area. Additionally, mini‐modules and stability testing are also carried out to demonstrate the feasibility of commercialization.

Unusual quadruple bonds featuring collective interaction-type σ bonds between first octal-row atoms in the alkaline-earth compounds AeOLi2 (Ae = Be-Ba).

Quantum chemical calculations are reported for the complexes of alkaline earth metals AeOLi2 (Ae = Be-Ba) at the BP86-D3(BJ)/def2-QZVPP and CCSD(T)/def2-QZVPPQZVPP levels. The nature of the Ae-OLi2 bond has been analyzed with a variety of methods. The AeOLi2 molecules exhibit an unprecedented σ donor bond Ae→OLi2 where the (n)s2 lone-pair electrons of the Ae atom are donated to vacant O-Li2 antibonding orbitals having the largest coefficient at lithium. This is a covalent bond where the accumulation of the associated electronic charge is located at two positions above and below the Ae-OLi2 axis. The bifurcated component of orbital interactions is structurally related to the recently proposed collective bonding model, but exhibits a completely different type of bonding. The most stable isomer of AeOLi2 has a C 2v geometry and a singlet (1A1) electronic ground state. The bond dissociation energy (BDE) of the Ae-OLi2 bonds exhibits a zig-zag trend from BeOLi2 to BaOLi2, with BeOLi2 having the largest BDE (D e = 73.0 kcal mol-1) and MgOLi2 possessing the lowest BDE (D e = 42.3 kcal mol-1) at the CCSD(T) level. The calculation of the atomic partial charges by the Hirshfeld and Voronoi methods suggests that Be and Mg carry small negative charges in the lighter molecules whereas the heavier atoms Ca-Ba have small positive charges. In contrast, the NBO and QTAIM methods give positive charges for all Ae atoms that are larger for Ca-Ba than that calculated by the Hirshfeld and Voronoi approaches. The molecules AeOLi2 have large dipole moments where the negative end is at the Ae atom with the polarity Ae→OLi2. The largest dipole moments are predicted for the lighter species BeOLi2 and MgOLi2 and the smallest value is calculated for BaOLi2. The calculation of the vibrational spectra shows a significant red-shift toward lower wave numbers for the Ae-OLi2 stretching mode in comparison to diatomic AeO. Besides the Ae→OLi2 σ-donor bonds there are also three dative bonds due to Ae←OLi2 backdonation which consist of one σ bond and two π bonds. The appearance of strong Ae→OLi2 σ donation leads to quadruple bonds AeOLi2 in all systems AeOLi2, even for the lightest species with Ae = Be, Mg. The valence orbitals of Ca, Sr, and Ba, which are involved in the dative interactions, are the (n)s and (n-1)d AOs whereas Be and Mg use their (n)s and (n)p AOs. The EDA-NOCV results are supported by the AdNDP calculations which give four 2c-2e bonding orbitals. Three bonding orbitals have occupation numbers ∼2. One σ orbital has smaller occupation numbers between 1.32 and 1.73 due to the delocalization to the lithium atoms. The analysis of the electronic structure with the ELF method suggests multicenter bonds with mainly trisynaptic and tetrasynaptic basins, which also support the results of the EDA-NOCV calculations.

Ions and dipoles in electric field: nonlinear polarization and field-dependent chemical reaction.

We investigate electric-field effects in dilute electrolytes with nonlinear polarization. As a first example of such systems, we add a dipolar component with a relatively large dipole moment [Formula: see text] to an aqueous electrolyte. As a second example, the solvent itself exhibits nonlinear polarization near charged objects. For such systems, we present a Ginzburg-Landau free energy and introduce field-dependent chemical potentials, entropy density, and stress tensor, which satisfy general thermodynamic relations. In the first example, the dipoles accumulate in high-field regions, as predicted by Abrashikin et al.[Phys.Rev.Lett. 99, 077801 (2007)]. Finally, we consider the case, where Bjerrum ion pairs form a dipolar component with nonlinear polarization. The Bjerrum dipoles accumulate in high-field regions, while field-induced dissociation was predicted by Onsager [J. Chem. Phys.2, 599 (1934)]. We present an expression for the field-dependent association constant K(E), which depends on the field strength nonmonotonically.

Electromagnetically induced transparency spectra of cesium Rydberg atoms decorated by radio-frequency fields

<sec>The large electric dipole moment of the Rydberg atom allows for strong coupling with weak electric fields, and is widely used in electric field measurements because of its reproducibility, precision and stability. The combination of Rydberg atoms and electromagnetically induced transparency (EIT) technology has been used for detecting and characterizing radio-frequency (RF) electric fields. </sec><sec>In this work, by selecting probe light (852 nm), dressed light (1470 nm), and coupled light (780 nm), the Rydberg state (49<i>P</i><sub>3/2</sub>) of Cs atom is prepared by using a three-photon excitation scheme through using all-infrared light excitation of Rydberg atoms. We experimentally observe the EIT spectra of the Rydberg states decorated by radio-frequency electric fields, which optically detects Rydberg atoms. The effect of the amplitude and frequency of the RF electric field on the spectrum is explored in light of changes in the EIT spectrum. The results show that in the region of weak electric field, only the ac Stark energy shift and spectral broadening occur. As the electric field is further enhanced, the sideband phenomenon occurs in both the primary peak and secondary peak of the EIT. In the region of strong field, the Rydberg energy level produces a series of Floquet states with higher-order terms, as well as state shifting and mixing, resulting in asymmetry in the spectra of the EIT sideband peaks. The effect of frequency on the shielding effect of the Cs vapor cell is further discussed based on the shift of the main peak of the EIT.</sec><sec>The demodulation of the electric field in a range of 50 Hz–1 kHz with a fidelity of 95% is achieved by modulating the low-frequency electric field to the RF electric field. The results can provide valuable references for spectral detection and traceable measurements of low-frequency electric fields.</sec>

Sensitivity of radio-frequency electric field sensor based on Rydberg Stark effect

Rydberg atoms hold special attraction in electric applications due to their large transition electric dipole moments and huge polarization, which leads to a strong response of atom to electric fields. In radio-frequency (RF) fields, the Rydberg levels are AC Stark shift and splitting, which can realize the study of high-sensitivity electric field sensor of Rydberg atoms. In this work, we use the simpler Shirley’s time-independent Floquet Hamiltonian model to calculate the AC Stark energy spectrum of Cs Rydberg atoms. This model can reduce the basic Hamiltonian into such a Hamiltonian that includes only those Rydberg states that have direct dipole-allowed transitions with the target state, thereby significantly improving the speed of computation. The accuracy of the calculation is proved by fitting with the calculated frequency shift of DC Stark energy levels in the weak fields, and the polarizability of 60D<sub>5/2</sub> and 70D<sub>5/2</sub> Rydberg atomic states are obtained by fitting with the measured ion spectra of DC Stark Cs ultra-cold Rydberg atoms in magneto-optical trap. In addition, we calculate the AC Stark shift of Cs Rydberg atom <inline-formula><tex-math id="M2">\begin{document}$ \left| {60{{\text{D}}_{5/2}},{m_j} = 1/2} \right\rangle $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240162_M2.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240162_M2.png"/></alternatives></inline-formula> state in electric fields with different frequencies with <i>ε</i> = 100 mV/m. Rydberg atoms provide a structured spectrum of sensitivity to electric fields due to strong resonant interaction and off-resonant interaction with many dipole-allowed transitions to nearby Rydberg states. This kind of the frequency response structure is of significance to a broadband sensor. And we calculate the sensitivity and the scaling of the signal-to-noise ratio (SNR), <i>β</i>, varying with detuning from the <inline-formula><tex-math id="M3">\begin{document}$ \left| {60{{\text{D}}_{5/2}}} \right\rangle \to \left| {61{{\text{P}}_{3/2}}} \right\rangle $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240162_M3.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20240162_M3.png"/></alternatives></inline-formula> transition. The value of <i>β</i> allows one to use the result for any Rydberg state sensor to determine the SNR for any <i>Ε</i> in a 1 s measurement. Therefrom, Rydberg sensor can preferentially detect many RF frequencies spreading across its carrier spectral range without modification while effectively rejecting large portions where the atom response is significantly weaker, and the signal depends primarily on the detuning of the RF field to the nearest resonance which does not convey the RF frequency directly.

Construction and fine tuning of host-guest doping systems and the underlying mechanism of room temperature phosphorescence

To obtain ultralong and efficient pure organic room temperature phosphorescent materials, as well as explore the intrinsic mechanisms affecting the phosphorescence performance of host-guest doping systems, two carbazole derivatives with the same molecular structure, named as L-CzIPCN and CzIPCN, were prepared by using carbazole synthesized in the laboratory and commercial carbazole. By choosing L-CzIPCN/CzIPCN and polymethyl methacrylate (PMMA)/polyvinyl alcohol (PVA)/benzophenone derivatives (BP, F-BP, Br-BP, and DF-BP) as the guest and host respectively, a series of new doping systems were constructed, and optimized by tuning doping ratios between host and guest materials. Among of them, F-BP/L-CzIPCN shows the longest room temperature phosphorescence (RTP) lifetime (501.23 ms), with RTP quantum yield of 31.19 %, followed by 0.2 % L-CzIPCN@PVA film (221.66 ms, 5.86 %) and 0.2 % L-CzIPCN@PMMA film (102.73 ms, 4.28 %) respectively. Moreover, L-CzIPCN displays different RTP spectra in diverse hosts, with dual-band RTP emission at 550 nm and 600 nm in benzophenone derivatives, but single RTP emission maxima in PMMA films, as well as a main emission peak at 470–510 nm and a shoulder peak at 550–590 nm in PVA films. The UV–Vis absorption spectra, fluorescence and phosphorescence spectra, and theoretical calculations indicate that RTP comes from the guest monomers in benzophenone derivatives/L-CzIPCN doping systems, with local triple characteristics, and host materials with large dipole moment, appropriate T1 energy level, and small energy gap between S1 and T1 contribute to improving RTP performance of the doping systems. Based on the excellent luminescence and different RTP lifetimes of the doping systems, some high-level anti-counterfeiting, and information encryption patterns were successfully constructed.

Molecular Engineering of Perylene Diimide Polymers with a Robust Built-in Electric Field for Enhanced Solar-Driven Water Splitting.

The built-in electric field of the polymer semiconductors could be regulated by the dipole moment of its building blocks, thereby promoting the separation of photogenerated carriers and achieving efficient solar-driven water splitting. Herein, three perylene diimide (PDI) polymers, namely oPDI, mPDI and pPDI, are synthesized with different phenylenediamine linkers. Notably, the energy level structure, light-harvesting efficiency, and photogenerated carrier separation and migration of polymers are regulated by the orientation of PDI unit. Among them, oPDI enables a large dipole moment and robust built-in electric field, resulting in enhanced solar-driven water splitting performance. Under simulated sunlight irradiation, oPDI exhibits the highest photocurrent of 115.1 μA cm-2 for photoelectrochemical oxygen evolution, which is 11.5 times that of mPDI, 26.8 times that of pPDI and 104.6 times that of its counterparts PDI monomer at the same conditions. This work provides a strategy for designing polymers by regulating the orientation of structural units to construct efficient solar energy conversion systems.

Molecular Engineering of Perylene Diimide Polymers with a Robust Built‐in Electric Field for Enhanced Solar‐Driven Water Splitting

AbstractThe built‐in electric field of the polymer semiconductors could be regulated by the dipole moment of its building blocks, thereby promoting the separation of photogenerated carriers and achieving efficient solar‐driven water splitting. Herein, three perylene diimide (PDI) polymers, namely oPDI, mPDI and pPDI, are synthesized with different phenylenediamine linkers. Notably, the energy level structure, light‐harvesting efficiency, and photogenerated carrier separation and migration of polymers are regulated by the orientation of PDI unit. Among them, oPDI enables a large dipole moment and robust built‐in electric field, resulting in enhanced solar‐driven water splitting performance. Under simulated sunlight irradiation, oPDI exhibits the highest photocurrent of 115.1 μA cm−2 for photoelectrochemical oxygen evolution, which is 11.5 times that of mPDI, 26.8 times that of pPDI and 104.6 times that of its counterparts PDI monomer at the same conditions. This work provides a strategy for designing polymers by regulating the orientation of structural units to construct efficient solar energy conversion systems.

Nano-second life time decay and Z-scan measurement: A tool to investigate the relevance of excited state dynamics with non-linear optical parameters in cis substituted Wells-Dawson POM-Porphyrin hybrids

Materials possessing non-linear optical NLO responses have gained considerable attention in the field of photonics because they have the potential to produce new frequencies when they interact with intense light by means of non-linear interactions. Synthesizing NLO materials based on porphyrin covalently bonded with polyoxometalates (POMs) is complicated and rigorous, requiring special techniques in order to get pure compounds with a higher yield. Here, we study the third-order NLO parameters along with the fluorescence lifetime decay values in a nanosecond(ns) time span for WDPOMCis2PyP and WDPOMCis2PhP (bearing the Wells-Dawson POM at the cis position) and their porphyrin precursors Cis2PyPTris and Cis2PhPTris, respectively. A comparison of third-order NLO characteristics with fluorescence lifetime decay data indicates that an increase in NLO properties has been observed with shorter lifetime decay values and vice versa. From the results, it is clear that WDPOMCis2PhP showed better third-order NLO (χ3 = 2.60 × 10−10 esu and β = 8.26 × 10−11 cm/W) than WDPOMCis2PyP (χ3 = 2.25 × 10−10 esu and β = 5.60 × 10−11 cm/W), which is supported by lifetime decay values. The lifetime decay value for WDPOMCis2PhP (τ1 = 2.77 ns) is shorter than WDPOMCis2PyP (τ1 = 6.02 ns). In addition to the factors mentioned based on substituent impact and molecular geometry, the WDPOMCis2PyP has a larger dipole moment than other POM-based porphyrin hybrids, which accounts for the improved third-order NLO response. Minor energy variance among singlet, triplet excited states, and charge-separated states favors quicker intersystem crossing of the WDPOMCis2PyP and WDPOMCis2PhP, which boosts NLO responses, and this actually makes WDPOMCis2PyP and WDPOMCis2PhP better than their corresponding POMs free porphyrins Cis2PyPTris and Cis2PhPTris, leading to their uses in optical devices.

Solvatochromic shifts and solvent effects on the electronic and transport behaviour of 1-Chloro Adamantane

Solvent influence on the photophysical and electronic properties of 1-Chloro Adamantane (CAD) are investigated using experimental and computational methods. Measured UV–vis absorption of CAD in various solvents exhibits substantial solvatochromatic shifts with respect to the solvent polarity. As a result of this, optical absorption of CAD undergoes the bathochromic shifts in the nonpolar solvents and hypsochromic shifts in the polar solvents with respect to polarity. Theoretical computations of EOM-CCSD and CIS quantum chemical methods calculated by means of SMD solvation model demonstrate the solvent influence on the electronic structure of CAD which are in good agreement with the experimental results. Computed results show prominent solvation effect on Lewis and non-Lewis occupancies. Large excited state dipole moment of the CAD in various solvation suggests excited states are more polarized than the ground state. In addition to this, molecular polarizabilities and energies of HOMO and LUMO show dominant solvent effects on the chemical reactivity of the CAD upon solvation. This solvent specific behaviour of CAD finds applications in optical filters with its significant hydrophobic nature.

Facilitating charge separation and migration of conjugated microporous polymers via skeleton isomerism engineering for photocatalytic reduction of uranium (VI)

Photoreduction of highly toxic and high-mobility UVI into insoluble UIV via conjugated microporous polymers (CMPs) is an effective way to extract uranium from highly acidic wastewater. Nevertheless, undesirable charge separation and migration, as well as rapid reverse charge recombination resulted in unsatisfactory photocatalytic activity of most CMPs. Herein, a pair of D-A CMPs for uranium photocatalytic reduction was developed by modulating skeleton isomerism through isomeric building blocks, named PQ-TPM (with phenanthrenequinone skeleton) and AQ-TPM (with anthraquinone skeleton). Interestingly, compared with anthraquinone skeleton CMP, phenanthrenequinone skeleton CMP can inhibit reverse charge recombination while promoting charge separation and migration due to its stronger built-in electric field and larger dipole moment. Therefore, PQ-TPM achieves an ultra-high photocatalytic UVI removal efficiency of 80.0 % within 180 min visible-light irradiation even under strongly acidic conditions (pH = 2), which was superior to AQ-TPM (30.0 %) and most reported CMPs. This study provides an unconventional concept and an emerging strategy for exploring outstanding CMPs photocatalysts for efficient processing of radionuclides.

An Azulene-Based Crystalline Porous Covalent Organic Framework for Efficient Photothermal Conversion.

The designed synthesis of a crystalline azulene-based covalent organic framework (COF-Azu-TP) is presented and its photothermal property is investigated. Azulene, a distinctive 5-7 fused ring non-benzenoid aromatic compound with a large intramolecular dipole moment and unique photophysical characteristics, is introduced as the key feature in COF-Azu-TP. The incorporation of azulene moiety imparts COF-Azu-TP with broad-spectrum light absorption capability and interlayer dipole interactions, which makes COF-Azu-TP a highly efficient photothermal conversion material. Its polyurethane (PU) composite exhibits a solar-to-vapor conversion efficiency (97.2%) and displays a water evaporation rate (1.43kg m-2 h-1) under one sun irradiation, even at a very low dosage of COF-Azu-TP (2.2wt%). Furthermore, COF-Azu-TP is utilized as a filler in a polylactic acid (PLA)/polycaprolactone (PCL) composited shape memory material, enabling rapid shape recovery under laser stimulation. A comparison study with a naphthalene-based COF isomer further emphasizes the crucial role of azulene in enhancing photothermal conversion efficiency. This study demonstrates the significance of incorporating specific building blocks into COFs for the development of functional porous materials with enhanced properties, paving the way for future applications in diverse fields.