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1.
Jifu Sun Wanhua Wu Prof. Jianzhang Zhao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(26):8100-8112
Cyclometalated IrIII complexes with acetylide ppy and bpy ligands were prepared (ppy=2‐phenylpyridine, bpy=2,2′‐bipyridine) in which naphthal ( Ir‐2 ) and naphthalimide (NI) were attached onto the ppy ( Ir‐3 ) and bpy ligands ( Ir‐4 ) through acetylide bonds. [Ir(ppy)3] ( Ir‐1 ) was also prepared as a model complex. Room‐temperature phosphorescence was observed for the complexes; both neutral and cationic complexes Ir‐3 and Ir‐4 showed strong absorption in the visible range (ε=39600 M ?1 cm?1 at 402 nm and ε=25100 M ?1 cm?1 at 404 nm, respectively), long‐lived triplet excited states (τT=9.30 μs and 16.45 μs) and room‐temperature red emission (λem=640 nm, Φp=1.4 % and λem=627 nm, Φp=0.3 %; cf. Ir‐1 : ε=16600 M ?1 cm?1 at 382 nm, τem=1.16 μs, Φp=72.6 %). Ir‐3 was strongly phosphorescent in non‐polar solvent (i.e., toluene), but the emission was completely quenched in polar solvents (MeCN). Ir‐4 gave an opposite response to the solvent polarity, that is, stronger phosphorescence in polar solvents than in non‐polar solvents. Emission of Ir‐1 and Ir‐2 was not solvent‐polarity‐dependent. The T1 excited states of Ir‐2 , Ir‐3 , and Ir‐4 were identified as mainly intraligand triplet excited states (3IL) by their small thermally induced Stokes shifts (ΔEs), nanosecond time‐resolved transient difference absorption spectroscopy, and spin‐density analysis. The complexes were used as triplet photosensitizers for triplet‐triplet annihilation (TTA) upconversion and quantum yields of 7.1 % and 14.4 % were observed for Ir‐2 and Ir‐3 , respectively, whereas the upconversion was negligible for Ir‐1 and Ir‐4 . These results will be useful for designing visible‐light‐harvesting transition‐metal complexes and for their applications as triplet photosensitizers for photocatalysis, photovoltaics, TTA upconversion, etc. 相似文献
2.
Iridium(III) Complexes Bearing Pyrene‐Functionalized 1,10‐Phenanthroline Ligands as Highly Efficient Sensitizers for Triplet–Triplet Annihilation Upconversion 下载免费PDF全文
Yue Lu Junsi Wang Dr. Niamh McGoldrick Xiaoneng Cui Prof. Dr. Jianzhang Zhao Colin Caverly Dr. Brendan Twamley Dr. Gearoid M. Ó Máille Bryan Irwin Robert Conway‐Kenny Prof. Dr. Sylvia M. Draper 《Angewandte Chemie (International ed. in English)》2016,55(47):14688-14692
“Chemistry‐on‐the‐complex” synthetic methods have allowed the selective addition of 1‐ethynylpyrene appendages to the 3‐, 5‐, 3,8‐ and 5,6‐positions of IrIII‐coordinated 1,10‐phenanthroline via Sonogashira cross‐coupling. The resulting suite of complexes has given rise to the first rationalization of their absorption and emission properties as a function of the number and position of the pyrene moieties. Strong absorption in the visible region (e.g. 3,8‐substituted Ir‐3 : λabs=481 nm, ?=52 400 m ?1 cm?1) and long‐lived triplet excited states (e.g. 5‐substituted Ir‐2 : τT=367.7 μs) were observed for the complexes in deaerated CH2Cl2. On testing the series as triplet sensitizers for triplet–triplet annihilation upconversion, those IrIII complexes bearing pyrenyl appendages at the 3‐ and 3,8‐positions ( Ir‐1 , Ir‐3 ) were found to give optimal upconversion quantum yields (30.2 % and 31.6 % respectively). 相似文献
3.
Wanhua Wu Prof. Jianzhang Zhao Dr. Huimin Guo Jifu Sun Shaomin Ji Zilong Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(7):1961-1968
Room‐temperature long‐lived near‐IR phosphorescence of boron‐dipyrromethene (BODIPY) was observed (λem=770 nm, ΦP=3.5 %, τP=128.4 μs). Our molecular‐design strategy is to attach PtII coordination centers directly onto the BODIPY π‐core using acetylide bonds, rather than on the periphery of the BODIPY core, thus maximizing the heavy‐atom effect of PtII. In this case, the intersystem crossing (ISC) is facilitated and the radiative decay of the T1 excited state of BODIPY is observed, that is, the phosphorescence of BODIPY. The complex shows strong absorption in the visible range (ε=53800 M ?1 cm?1 at 574 nm), which is rare for PtII–acetylide complexes. The complex is dual emissive with 3M LCT emission at 660 nm and the 3IL emission at 770 nm. The T1 excited state of the complex is mainly localized on the BODIPY moiety (i.e. 3IL state, as determined by steady‐state and time‐resolved spectroscopy, 77 K emission spectra, and spin‐density analysis). The strong visible‐light‐harvesting ability and long‐lived T1 excite state of the complex were used for triplet‐triplet annihilation based upconversion and an upconversion quantum yield of 5.2 % was observed. The overall upconversion capability (η=ε×ΦUC) of this complex is remarkable considering its strong absorption. The model complex, without the BODIPY moiety, gives no upconversion under the same experimental conditions. Our work paves the way for access to transition‐metal complexes that show strong absorption of visible light and long‐lived 3IL excited states, which are important for applications in photovoltaics, photocatalysis, and upconversions, etc. 相似文献
4.
Pd–Porphyrin Oligomers Sensitized for Green‐to‐Blue Photon Upconversion: The More the Better? 下载免费PDF全文
Dr. Zhiqing Xun Dr. Yi Zeng Dr. Jinping Chen Dr. Tianjun Yu Dr. Xiaohui Zhang Prof. Dr. Guoqiang Yang Prof. Dr. Yi Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(25):8654-8662
A series of directly meso‐meso‐linked Pd–porphyrin oligomers (PdDTP‐M, PdDTP‐D, and PdDTP‐T) have been prepared. The absorption region and the light‐harvesting ability of the Pd–porphyrin oligomers are broadened and enhanced by increasing the number of Pd–porphyrin units. Triplet–triplet annihilation upconversion (TTA‐UC) systems were constructed by utilizing the Pd–porphyrin oligomers as the sensitizer and 9,10‐diphenylanthracene (DPA) as the acceptor in deaerated toluene and green‐to‐blue photon upconversion was observed upon excitation with a 532 nm laser. The triplet–triplet annihilation upconversion quantum efficiencies were found to be 6.2 %, 10.5 %, and 1.6 % for the [PdDTP‐M]/DPA, [PdDTP‐D]/DPA, and [PdDTP‐T]/DPA systems, respectively, under an excitation power density of 500 mW cm?2. The photophysical processes of the TTA‐UC systems have been investigated in detail. The higher triplet–triplet annihilation upconversion quantum efficiency observed in the [PdDTP‐D]/DPA system can be rationalized by the enhanced light‐harvesting ability of PdDTP‐D at 532 nm. Under the same experimental conditions, the [PdDTP‐D]/DPA system produces more 3DPA* than the other two TTA‐UC systems, benefiting the triplet–triplet annihilation process. This work provides a useful way to develop efficient TTA‐UC systems with broad spectral response by using Pd–porphyrin oligomers as sensitizers. 相似文献
5.
Dr. Yinghui Wang Prof. Bin Li Liming Zhang Qinghui Zuo Peng Li Dr. Jun Zhang Prof. Zhongmin Su 《Chemphyschem》2011,12(2):349-355
An optical oxygen sensor based on an EuIII complex/polystyrene (PS) composite nanofibrous membrane is prepared by electrospinning. The emission intensity of [Eu(TTA)3(phencarz)] (TTA=2‐thenoyltrifluoroacetonate, phencarz=2‐(N‐ethylcarbazolyl‐4)imidazo[4,5‐f]1,10‐phenanthroline) decreases with increasing oxygen concentration, and thus the [Eu(TTA)3 (phencarz)]/PS composite nanofibrous membranes can be used as an optical oxygen‐sensing material based on emission quenching caused by oxygen. Elemental analysis, UV/Vis absorption spectra, scanning electron microscopy (SEM), fluorescence microscopy, luminescence‐intensity quenching Stern–Volmer plots, and excited‐state decay analysis are used to characterize the obtained oxygen‐sensing materials. A high sensitivity (IN2/IO2) of 3.38 and short response and recovery times (t↓=5.0, t↑=8.0 s) are obtained. These results are the best values reported for oxygen sensors based on EuIII complexes. The high surface area‐to‐volume ratio and porous structure of the electrospun nanofibrous membranes are taken to be responsible for the outstanding performance. 相似文献
6.
A Fluorescent Molecular Probe for the Detection of Hydrogen Based on Oxidative Addition Reactions with Crabtree‐Type Hydrogenation Catalysts 下载免费PDF全文
M. Sc. Pavlo Kos Prof. Dr. Herbert Plenio 《Angewandte Chemie (International ed. in English)》2015,54(45):13293-13296
A Crabtree‐type IrI complex tagged with a fluorescent dye (bodipy) was synthesized. The oxidative addition of H2 converts the weakly fluorescent IrI complex (Φ=0.038) into a highly fluorescent IrIII species (Φ=0.51). This fluorogenic reaction can be utilized for the detection of H2 and to probe the oxidative addition step in the catalytic hydrogenation of olefins. 相似文献
7.
Christopher E. Elgar Haleema Y. Otaif Xue Zhang Prof. Jianzhang Zhao Dr. Peter N. Horton Prof. Simon J. Coles Dr. Joseph M. Beames Prof. Simon J. A. Pope 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(10):3427-3439
Six substituted ligands based upon 2-(naphthalen-1-yl)quinoline-4-carboxylate and 2-(naphthalen-2-yl)quinoline-4-carboxylate have been synthesised in two steps from a range of commercially available isatin derivatives. These species are shown to be effective cyclometallating ligands for IrIII, yielding complexes of the form [Ir(C^N)2(bipy)]PF6 (where C^N=cyclometallating ligand; bipy=2,2′-bipyridine). X-ray crystallographic studies on three examples demonstrate that the complexes adopt a distorted octahedral geometry wherein a cis-C,C and trans-N,N coordination mode is observed. Intraligand torsional distortions are evident in all cases. The IrIII complexes display photoluminescence in the red part of the visible region (668–693 nm), which is modestly tuneable through the ligand structure. The triplet lifetimes of the complexes are clearly influenced by the precise structure of the ligand in each case. Supporting computational (DFT) studies suggest that the differences in observed triplet lifetime are likely due to differing admixtures of ligand-centred versus MLCT character instilled by the facets of the ligand structure. Triplet–triplet annihilation upconversion (TTA-UC) measurements demonstrate that the complexes based upon the 1-naphthyl derived ligands are viable photosensitisers with upconversion quantum efficiencies of 1.6–6.7 %. 相似文献
8.
Wen‐Juan Xu Shu‐Juan Liu Dr. Xin‐Yan Zhao Shi Sun Shan Cheng Ting‐Chun Ma Hui‐Bin Sun Qiang Zhao Dr. Wei Huang Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(24):7125-7133
A novel cationic IrIII complex [Ir(Bpq)2(CzbpyCz)]PF6 (Bpq=2‐[4‐(dimesitylboryl)phenyl]quinoline, CzbpyCz = 5,5′‐bis(9‐hexyl‐9H‐carbazol‐3‐yl)‐2,2′‐bipyridine) containing both triarylboron and carbazole moieties was synthesized. The excited‐state properties of [Ir(Bpq)2(CzbpyCz)]PF6 were investigated through UV/Vis absorption and photoluminescence spectroscopy and molecular‐orbital calculations. This complex displayed highly efficient orange‐red phosphorescent emission with an emission peak of 583 nm and quantum efficiency of Φ=0.30 in dichloromethane at room temperature. The binding of fluoride ions to [Ir(Bpq)2(CzbpyCz)]PF6 can quench the phosphorescent emission from the IrIII complex and enhance the fluorescent emission from the N^N ligand, which corresponds to a visual change in the emission from orange‐red to blue. Thus, both colorimetric and ratiometric fluoride sensing can be realized. Interestingly, an unusual intense absorption band in the visible region was observed. And the detection of F? ions can also be carried out with visible light as the excitation wavelength. More importantly, the linear response of the probe absorbance change at λ=351 nm versus the concentration of F? ions allows efficient and accurate quantification of F? ions in the range 0–50 μM . 相似文献
9.
Zhijia Wang Ling Huang Yuxin Yan Ahmed M. El‐Zohry Antonio Toffoletti Jianzhang Zhao Antonio Barbon Bernhard Dick Omar F. Mohammed Gang Han 《Angewandte Chemie (International ed. in English)》2020,59(37):16114-16121
Intersystem crossing (ISC) of triplet photosensitizers is a vital process for fundamental photochemistry and photodynamic therapy (PDT). Herein, we report the co‐existence of efficient ISC and long triplet excited lifetime in a heavy atom‐free bodipy helicene molecule. Via theoretical computation and time‐resolved EPR spectroscopy, we confirmed that the ISC of the bodipy results from its twisted molecular structure and reduced symmetry. The twisted bodipy shows intense long wavelength absorption (?=1.76×105 m ?1 cm?1 at 630 nm), satisfactory triplet quantum yield (ΦT=52 %), and long‐lived triplet state (τT=492 μs), leading to unprecedented performance as a triplet photosensitizer for PDT. Moreover, nanoparticles constructed with such helical bodipy show efficient PDT‐mediated antitumor immunity amplification with an ultra‐low dose (0.25 μg kg?1), which is several hundred times lower than that of the existing PDT reagents. 相似文献
10.
Dr. Zuo‐Qin Liang Bin Sun Dr. Chang‐Qing Ye Prof. Xiao‐Mei Wang Prof. Xu‐Tang Tao Prof. Qin‐Hua Wang Ping Ding Bao Wang Jing‐Jing Wang 《Chemphyschem》2013,14(15):3517-3522
Three new anthracene derivatives [2‐chloro‐9,10‐dip‐tolylanthracene (DTACl), 9,10‐dip‐tolylanthracene‐2‐carbonitrile (DTACN), and 9,10‐di(naphthalen‐1‐yl)anthracene‐2‐carbonitrile (DNACN)] were synthesized as triplet acceptors for low‐power upconversion. Their linear absorption, single‐photon‐excited fluorescence, and upconversion fluorescence properties were studied. The acceptors exhibit high fluorescence yields in DMF. Selective excitation of the sensitizer PdIIoctaethylporphyrin (PdOEP) in solution containing DTACl, DTACN, or DNA‐CN at 532 nm with an ultralow excitation power density of 0.5 W cm?2 results in anti‐Stokes blue emission. The maximum upconversion quantum yield (ΦUC=17.4 %) was obtained for the couple PdOEP/DTACl. In addition, the efficiency of the triplet–triplet energy transfer process was quantitatively studied by quenching experiments. Experimental results revealed that a highly effective acceptor for upconversion should combine high fluorescence quantum yields with efficient quenching of the sensitizer triplet. 相似文献
11.
Yi X Zhao J Wu W Huang D Ji S Sun J 《Dalton transactions (Cambridge, England : 2003)》2012,41(29):8931-8940
The preparation of rhenium(I) tricarbonyl polypyridine complexes that show a strong absorption of visible light and long-lived triplet excited state and the application of these complexes as triplet photosensitizers for triplet-triplet annihilation (TTA) based upconversion are reported. Imidazole-fused phenanthroline was used as the N^N coordination ligand, on which different aryl groups were attached (Phenyl, Re-0; Coumarin, Re-1 and naphthyl, Re-2). Re-1 shows strong absorption of visible light (ε = 60,800 M(-1) cm(-1) at 473 nm). Both Re-1 and Re-2 show long-lived T(1) states (lifetime, τ(T), is up to 86.0 μs and 64.0 μs, respectively). These properties are in contrast to the weak absorption of visible light and short-lived triplet excited states of the normal rhenium(I) tricarbonyl polypyridine complexes, such as Re-0 (ε = 5100 M(-1) cm(-1) at 439 nm, τ(T) = 2.2 μs). The photophysical properties of the complexes were fully studied with steady state and time-resolved absorption and emission spectroscopes, as well as DFT calculations. The intra-ligand triplet excited state is proposed to be responsible for the exceptionally long-lived T(1) states of Re-1 and Re-2. The Re(I) complexes were used as triplet photosensitizers for TTA based upconversion and an upconversion quantum yield up to 17.0% was observed. 相似文献
12.
Bipyrimidines have been chosen as (N∧N)(N∧N) bridging ligands for connecting metal centers. IrIII-LnIII (Ln = Nd, Yb, Er) bimetallic complexes [Ir(dfppy)2(μ-bpm)Ln(TTA)3]Cl were synthesized by using Ir(dfppy)2(bpm)Cl as the ligand coordinating to lanthanide complexes Ln(TTA)3·2H2O. The stability constants between Ir(dfppy)2(bpm)Cl and lanthanide ions were measured by fluorescence titration. The obvious quenching of visible emission from IrIII complex in the IrIII-LnIII (Ln = Nd, Yb, Er) bimetallic complexes indicates that energy transfer occurred from IrIII center to lanthanides. NIR emissions from NdIII, YbIII, and ErIII were obtained under the excitation of visible light by selective excitation of the IrIII-based chromophore. It was proven that Ir(dfppy)2(bpm)Cl as the ligand could effectively sensitize NIR emission from NdIII, YbIII, and ErIII. 相似文献
13.
Dr. Kepeng Chen Ivan V. Kurganskii Xue Zhang Prof. Ayhan Elmali Prof. Jianzhang Zhao Dr. Ahmet Karatay Prof. Matvey V. Fedin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(27):7572-7587
Anthracene-naphthalimide (An-NI) compact electron donor-acceptor dyads were prepared, in which the orientation and distance between the two subunits were varied by direct connection or with intervening phenyl linker. Efficient intersystem crossing (ISC) and long triplet state lifetime (ΦΔ=92 %, τT=438 μs) were observed for the directly connected dyads showing a perpendicular geometry (81°). This efficient spin-orbit charge transfer ISC (SOCT-ISC) takes 376 fs, inhibits the direct charge recombination (CR) to ground state (1CT→S0, takes 3.04 ns). Interestingly, efficient SOCT-ISC for dyads with intervening phenyl linker (ΦΔ=40 % in DCM) was also observed, although the electron donor and acceptor adopt almost coplanar geometry (dihedral angle: 15°). Time-resolved electron paramagnetic resonance (TREPR) spectroscopy shows that the electron spin polarization of the triplet state, i. e. the electron spin selectivity of ISC, is highly dependent on the dihedral angle and the linker. For the dyads showing weaker coupling between the donor and acceptors, the charge separation and the intramolecular triplet energy transfer are inhibited at 80 K (frozen solution), because both the 3An and 3NI states were observed and the ESP are same as compared to the native anthracene and naphthalimide, which unravel their origin. The dyads were used as triplet photosensitizers for triplet−triplet annihilation upconversion (TTA UC). High UC quantum yield (ΦUC=12.9 %) as well as a large anti-Stokes shift (0.72 eV) was attained by excitation into the CT absorption band. 相似文献
14.
Unprecedented Sensitization of Visible and Near‐Infrared Lanthanide Luminescence by Using a Tetrathiafulvalene‐Based Chromophore 下载免费PDF全文
Min Feng Dr. Fabrice Pointillart Dr. Boris Le Guennic Bertrand Lefeuvre Dr. Stéphane Golhen Dr. Olivier Cador Dr. Olivier Maury Dr. Lahcène Ouahab 《化学:亚洲杂志》2014,9(10):2814-2825
Ligand L was synthesized and then coordinated to [Ln(hfac)3] ? 2 H2O (LnIII=Tb, Dy, Er; hfac?=1,1,1,5,5,5‐hexafluoroacetylacetonate anion) and [Ln(tta)3]?2 H2O (LnIII=Eu, Gd, Tb, Dy, Er, Yb; tta?=2‐thenoyltrifluoroacetonate) to give two families of dinuclear complexes [Ln2(hfac)6( L )] ? C6H14 and [Ln2(tta)6( L )] ? 2 CH2Cl2. Irradiation of the ligand at 37 040 cm?1 and 29 410 cm?1 leads to tetrathiafulvalene‐centered and 2,6‐di(pyrazol‐1‐yl)‐4‐pyridine‐centered fluorescence, respectively. The ligand acts as an organic chromophore for the sensitization of the infrared ErIII (6535 cm?1) and YbIII (10 200 cm?1) luminescence. The energies of the singlet and triplet states of L are high enough to guarantee an efficient sensitization of the visible EuIII luminescence (17 300–14 100 cm?1). The EuIII luminescence decay can be nicely fitted by a monoexponential function that allows a lifetime estimation of (0.49±0.01) ms. Finally, the magnetic and luminescence properties of [Yb2(hfac)6( L )] ? C6H14 were correlated, which allowed the determination of the crystal field splitting of the 2F7/2 multiplet state with MJ=±1/2 as ground states. 相似文献
15.
Kaiyue Ye Peili Wang Minjie Li Dr. Yuqi Hou Prof. Jianzhang Zhao Prof. Yan Wan 《欧洲无机化学杂志》2023,26(19):e202300142
We prepared a N^N Pt(II) bisacetylide complex that has strong absorption of visible light (molar absorption coefficients ϵ=6.7×104 M−1 cm−1 at 570 nm), and the singlet oxygen quantum yield (ΦΔ) is up to 78 %. Femtosecond transient absorption spectra show the intersystem crossing (ISC) of the complex takes 81.8 ps, nanosecond transient absorption spectra show the triplet excited state lifetime is 7.6 μs. Density functional theory (DFT) computation demonstrated that the S1 and T1 states are mainly localized on the perylenemonoimide (PMI) ligands, although the involvement of the Pt(II) centre is noticeable. The complex was used as triplet photosensitizer to generate delayed fluorescence with perylenebisimide (PBI) as the triplet state energy acceptor and emitter, via the intermolecular triplet-triplet energy transfer (TTET) and triplet-triplet annihilation (TTA), the delayed fluorescence lifetime is up to 52.5 μs under the experimental conditions. 相似文献
16.
Chiral Sensing of Various Amino Acids Using Induced Circularly Polarized Luminescence from Europium(III) Complexes of Phenanthroline Dicarboxylic Acid Derivatives 下载免费PDF全文
Circularly polarized luminescence (CPL) was observed from [Eu(dppda)2]? (dppda=4,7‐diphenyl‐1,10‐phenanthroline‐2,9‐dicarboxylic acid) and [Eu(pzpda)2]? (pzpda=pyrazino[2,3‐f][1,10]phenanthroline‐7,10‐dicarboxylic acid) in aqueous solutions containing various amino acids. The selectivity of these complexes towards amino acids enabled them to be used as chiral sensors and their behavior was compared with that of [Eu(pda)2]? (pda=1,10‐phenanthroline‐2,9‐dicarboxylic acid). As these EuIII complexes have achiral D2d structures under ordinary conditions, there were no CPL signals in the emission assigned to f–f transitions. However, when the solutions contained particular amino acids they exhibited detectable CPL signals with glum values of about 0.1 (glum=CPL/2 TL; TL=total luminescence). On examining 13 amino acids with these three EuIII complexes, it was found that whether an amino acid induced a detectable CPL depended on the EuIII complex ligands. For example, when ornithine was used as a chiral agent, only [Eu(dppda)2]? exhibited intense CPL in aqueous solutions of 10?2 mol dm?3. Steep amino acid concentration dependence suggested that CPL in [Eu(dppda)2]? and [Eu(pzpda)2]? was induced by the association of four or more amino acid molecules, whereas CPL in [Eu(pda)2]? was induced by association of two arginine molecules. 相似文献
17.
Dr. Fabrice Pointillart Dr. Thomas Cauchy Dr. Olivier Maury Yann Le Gal Dr. Stéphane Golhen Dr. Olivier Cador Dr. Lahcène Ouahab 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(39):11926-11941
The tetrathiafulvalene‐amido‐2‐pyridine‐N‐oxide ( L ) ligand has been employed to coordinate 4f elements. The architecture of the complexes mainly depends on the ionic radii of the lanthanides. Thus, the reaction of L in the same experimental protocol leads to three different molecular structure series. Binuclear [Ln2(hfac)5(O2CPhCl)( L )3] ? 2 H2O (hfac?=1,1,1,5,5,5‐hexafluoroacetylacetonate anion, O2CPhCl?=3‐chlorobenzoate anion) and mononuclear [Ln(hfac)3( L )2] complexes were obtained by using rare‐earth ions with either large (LnIII=Pr, Gd) or small (LnIII=Y, Yb) ionic radius, respectively, whereas the use of TbIII that possesses an intermediate ionic radius led to the formation of a binuclear complex of formula [Tb2(hfac)4(O2CPhCl)2( L )2]. Antiferromagnetic interactions have been observed in the three dinuclear compounds by using an extended empirical method. Photophysical properties of the coordination complexes have been studied by solid‐state absorption spectroscopy, whereas time‐dependent density functional theory (TD‐DFT) calculations have been carried out on the diamagnetic YIII derivative to build a molecular orbital diagram and to reproduce the absorption spectrum. For the [Yb(hfac)3( L )2] complex, the excitation at 19 600 cm?1 of the HOMO→LUMO+1/LUMO+2 charge‐transfer transition induces both line‐shape emissions in the near‐IR spectral range assigned to the 2F5/2→2F7/2 (9860 cm?1) ytterbium‐centered transition and a residual charge‐transfer emission around 13 150 cm?1. An efficient antenna effect that proceeds through energy transfer from the singlet excited state of the tetrathiafulvalene‐amido‐2‐pyridine‐N‐oxide chromophore is evidence of the YbIII sensitization. 相似文献
18.
Dr. Zafar Mahmood Noreen Rehmat Prof. Shaomin Ji Prof. Jianzhang Zhao Shanshan Sun Dr. Mariangela Di Donato Prof. Mingde Li Maria Teddei Prof. Yanping Huo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(65):14912-14918
Zinc(II) bis(dipyrrin) complexes, which feature intense visible absorption and efficient symmetry breaking charge transfer (SBCT) are outstanding candidates for photovoltaics but their short lived triplet states limit applications in several areas. Herein we demonstrate that triplet excited state dynamics of bis(dipyrrin) complexes can be efficiently tuned by attaching electron donating aryl moieties at the 5,5′-position of the complexes. For the first time, a long lived triplet excited state (τT=296 μs) along with efficient ISC ability (ΦΔ=71 %) was observed for zinc(II) bis(dipyrrin) complexes, formed via SBCT. The results revealed that molecular geometry and energy gap between the charge transfer (CT) state and triplet energy levels strongly control the triplet excited state properties of the complexes. An efficient triplet–triplet annihilation upconversion system was devised for the first time using a SBCT architecture as triplet photosensitizer, reaching a high upconversion quantum yield of 6.2 %. Our findings provide a blueprint for the development of triplet photosensitizers based on earth abundant metal complexes with long lived triplet state for revolutionary photochemical applications. 相似文献
19.
Giulia Lavarda Daiki Shimizu Toms Torres Atsuhiro Osuka 《Angewandte Chemie (International ed. in English)》2020,59(8):3127-3130
Peripherally metalated porphyrinoids are promising functional π‐systems displaying characteristic optical, electronic, and catalytic properties. In this work, 5‐(2‐pyridyl)‐ and 5,10,15‐tri(2‐pyridyl)‐BIII‐subporphyrins were prepared and used to produce cyclometalated subporphyrins by reactions with [Cp*IrCl2]2, which proceeded through an efficient C?H activation to give the corresponding mono‐ and tri‐IrIII complexes, respectively. While the mono‐IrIII complex was obtained as a diastereomeric mixture, a C3‐symmetric tri‐IrIII complex with the three Cp*‐units all at the concave side was predominantly obtained in a high yield of 90 %, which displays weak NIR phosphorescence even at room temperature in degassed CH2Cl2, differently from the mono‐IrIII complexes. 相似文献
20.
Adriana Valore Dr. Elena Cariati Prof. Dr. Claudia Dragonetti Dr. Stefania Righetto Dr. Dominique Roberto Prof. Dr. Renato Ugo Prof. Dr. Filippo De Angelis Dr. Simona Fantacci Dr. Antonio Sgamellotti Prof. Dr. Alceo Macchioni Prof. Dr. Daniele Zuccaccia Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(16):4814-4825
Cyclometalated cationic IrIII complexes with substituted 1,10‐phenanthrolines (1,10‐phen), such as [Ir(ppy)2(5‐R‐1,10‐phen)]Y (ppy=cyclometalated 2‐phenylpyridine; R=NO2, H, Me, NMe2; Y?=PF6?, C12H25SO3?, I?) and [Ir(ppy)2(4‐R,7‐R‐1,10‐phen)]Y (R=Me, Ph) are characterized by a significant second‐order optical non linearity (measured by the electrical field induced second harmonic generation (EFISH) technique). This nonlinearity is controlled by MLCT processes from the cyclometalated IrIII, acting as a donor push system, to π* orbitals of the phenanthroline, acting as an acceptor pull system. Substitution of cyclometalated 2‐phenylpyridine by the more π delocalized 2‐phenylquinoline (pq) or benzo[h]quinoline (bzq) or by the sulfur‐containing 4,5‐diphenyl‐2‐methyl‐thiazole (dpmf) does not significantly affect the μβ absolute value, which instead is affected by the nature of the R substituents on the phenanthroline, the higher value being associated with the electron‐withdrawing NO2 group. By using a combined experimental (the EFISH technique and 1H and 19F PGSE NMR spectroscopy) and theoretical (DFT, time‐dependent‐DFT (TDDFT), sum over states (SOS) approach) investigation, evidence is obtained that ion pairing, which is controlled by the nature of the counterion and by the concentration, may significantly affect the μβ values of these cationic NLO chromophores. In CH2Cl2, concentration‐dependent high absolute values of μβ are obtained for [Ir(ppy)2(5‐NO2‐1,10‐phen)]Y if Y is a weakly interacting anion, such as PF6?, whereas with a counterion, such as C12H25SO3? or I?, which form tight ion‐pairs, the absolute value of μβ is lower and quite independent of the concentration. This μβ trend is partially due to the perturbation of the counterion on the LUMO π* levels of the phenanthroline. The correlation between the μβ value and dilution shows that the effect of concentration is a factor that must be taken into careful consideration. 相似文献