Phosphorescence Spectra Research Articles

Development of an Organic Emitter Exhibiting Reverse Intersystem Crossing Faster than Intersystem Crossing

AbstractIn thermally activated delayed fluorescence (TADF)‐based organic light‐emitting diodes (OLEDs), acceleration of reverse intersystem crossing (RISC) and suppression of intersystem crossing (ISC) are demanded to shorten a lifetime of triplet excitons. As a system realizing RISC faster than ISC, inverted singlet‐triplet excited states (iST) with a negative energy difference (ΔEST) between the lowest excited singlet and the lowest triplet states have been gathering much attention recently. Here, we have focused on an asymmetric hexa‐azaphenalene (A6AP) core to obtain a new insight into iST. Based on A6AP, we have newly designed A6AP‐Cz with the calculated ΔEST of −44 meV. The experimental studies of a synthesized A6AP‐Cz revealed that the lifetime of delayed fluorescence (τDF) was only 54 ns, which was the shortest among all organic materials. The rate constant of RISC (kRISC=1.9×107 s−1) was greater than that of ISC (kISC=1.0×107 s−1). The negative ΔEST of A6AP‐Cz was experimentally confirmed from 1) the kRISC and kISC (−45 meV) and 2) the temperature‐dependent τDF. 3) The onsets of fluorescence and phosphorescence spectra at 77 K also supported the evidence of negative ΔEST (−73 meV). This study demonstrated the potential of A6AP as an iST core for the first time.

Development of an Organic Emitter Exhibiting Reverse Intersystem Crossing Faster than Intersystem Crossing.

In thermally activated delayed fluorescence (TADF)-based organic light-emitting diodes (OLEDs), acceleration of reverse intersystem crossing (RISC) and suppression of intersystem crossing (ISC) are demanded to shorten a lifetime of triplet excitons. As a system realizing RISC faster than ISC, inverted singlet-triplet excited states (iST) with a negative energy difference (ΔEST) between the lowest excited singlet and the lowest triplet states have been gathering much attention recently. Here, we have focused on an asymmetric hexa-azaphenalene (A6AP) core to obtain a new insight into iST. Based on A6AP, we have newly designed A6AP-Cz with the calculated ΔEST of -44 meV. The experimental studies of a synthesized A6AP-Cz revealed that the lifetime of delayed fluorescence (τDF) was only 54 ns, which was the shortest among all organic materials. The rate constant of RISC (kRISC=1.9×107 s-1) was greater than that of ISC (kISC=1.0×107 s-1). The negative ΔEST of A6AP-Cz was experimentally confirmed from 1) the kRISC and kISC (-45 meV) and 2) the temperature-dependent τDF. 3) The onsets of fluorescence and phosphorescence spectra at 77 K also supported the evidence of negative ΔEST (-73 meV). This study demonstrated the potential of A6AP as an iST core for the first time.

Exploring the Photophysics and Photocatalytic Activity of Heteroleptic Rh(III) Transition-Metal Complexes Using High-Throughput Experimentation.

High-throughput synthesis and screening (HTSS) methods were used to investigate the photophysical properties of 576 heteroleptic Rh(III) transition-metal complexes through measurement of the UV-visible absorption spectra, deaerated excited-state lifetime, and phosphorescent emission spectra. While 4d transition-metal photophysics are often highly influenced by deleterious metal-centered deactivation channels, the HTSS of structurally diverse cyclometalating and ancillary ligands attached to the metal center facilitated the discovery of photoactive complexes exhibiting long-lived charge-transfer phosphorescence (0.15-0.95 μs) spanning a substantial portion of the visible region (546-620 nm) at room temperature. Further photophysical and electrochemical investigations were then carried out on select complexes with favorable photophysics to understand the underlying features controlling these superior properties. Heteroleptic Ir(III) complexes with identical ligand morphology were also synthesized to compare these features to this family of well understood chromophores. A number of these Rh(III) complexes contained the requisite properties for photocatalytic activity and were consequently tested as photocatalysts (PCs) in a water reduction system using a Pd water reduction cocatalyst. Under certain conditions, the activity of the Rh(III) PC actually surpassed that of the Ir(III) PC, uncovering the potential of this often-overlooked class of transition metals as both efficient photoactive chromophores and PCs.

B-O-O-B Impurity Induces Ultralong Room-Temperature Phosphorescence of Boric Acid.

Organic materials that can emit ultralong room-temperature phosphorescence (RTP) have attracted a great deal of interest. Whether the pure boric acid (BA) solid can emit RTP and the origin of the RTP in BA caused a debate recently. Herein, our first-principles calculations and experimental measurements suggest that RTP of BA originates from the B-O-O-B group in a (H2BO3)2 species, which can be formed by polymerization of two dehydrogenated BA molecules under light irradiation. The calculated absorption, fluorescence, and phosphorescence spectra of B-O-O-B match well with the experiments. Experimental X-ray photoelectron and X-ray absorption spectra evidence the existence of B-O-O-B in BA. The O-O bond in B-O-O-B can break upon optical excitation, creating two B-O radicals. Radiative transition from localized dangling orbitals of the B-O radicals to the delocalized orbitals of the crystal bulk leads to the observed RTP. Our calculated phosphorescence lifetime is ∼1 s, which agrees well with the experiment.

An inverted singlet-triplet excited state in a pentaazaphenalene derivative (5AP-N(C12)2)

The characteristic of inverted singlet-triplet excited states, in which the lowest singlet excited state (S1) is lower than the lowest triplet state (T1) in energy, was observed in a dialkylamine-substituted pentaazaphenalene derivative, 5AP-N(C12)2. The transient photoluminescence measurements showed that the reverse intersystem crossing has virtually zero activation energy, whereas the intersystem crossing is proceeded by a thermal activation process. T1 was located energetically above S1 with a negative energy gap between S1 and T1 (ΔE ST) of −37 meV. Fluorescence and phosphorescence spectra also confirmed the negative ΔE ST of −46 to −32 meV.

ABSORPTION AND LUMINESCENCE PROPERTIES OF ACID AND SALT FORMS OF MONONUCLEOTIDES, THEIR COMPONENTS AND COMPLEXES WITH D-MANNITOL AT ROOM TEMPERATURE

Aim. The aim of this work was to analyze and compare spectral properties of aqueous nucleotide solutions in conditions close to biological systems. We studied the absorption and luminescence (Ex and Em fluorescence and Em phosphorescence) of monoribonucleotides, their disodium salts, bases and nucleosides, and mixes with D-mannitol dissolved in water at room temperature. Methods. There were measured absorbance spectra using a Specord 210plus instrument and fluorescence excitation and emission and phosphorescence spectra using Horiba Fluoro Max 4+ instruments. Results. There were obtained the absorption, excitation, and luminescence spectra of aqueous solutions 1 mg/ml of nucleotides, their components, and mixtures with mannitol (in ratio 1:4). We observed a change in the ratio between the peaks of the spectra of acidic and salt forms of nucleotides. Conclusions. The observations confirmed that nucleotides, nucleosides, and nucleic acid bases exhibit luminescence at room temperature, which might be useful information for further research in this area. In addition, a comparative analysis of the spectra showed possible interactions between nucleotide molecules and mannitol.

Preparation of Eu2+ and Dy3+ co-doped Sr2MgSi2O7 translucent long afterglow glass-ceramics by recrystallization-melting and their luminescence properties

In this work, a novel recrystallization-melting method was used to prepare Eu2+ and Dy3+ co-doped Sr2MgSi2O7 translucency long afterglow glass-ceramics with complete crystal development. The synthesis mechanism is discussed by analyzing the detection results of X-ray diffraction, scanning electron microscopy, phosphorescence spectra, and afterglow attenuation curves. The effect of different firing temperatures and crystallization time on the crystalline phase content, crystal size, and luminescence properties of the Sr2MgSi2O7:Eu2+, Dy3+ glass-ceramics samples were examined. The results show that, as compared with the traditional melt crystallization method or the two-step method, the recrystallization–melting method is able to form some Sr2MgSi2O7:Eu2+, Dy3+ crystals first under a temperature that is lower than that of the glass transition. With increasing firing temperature and crystallization time, crystal growth and recrystallization reached an equilibrium state, accompanied by the generation of liquid glassy phases. It is found that the afterglow properties are proportional to the crystalline phase content and crystal size, with the latter having a more significant effect. Under the condition of firing at 1050 °C for 10 h, tetragonal Sr2MgSi2O7 crystals with a maximum size of 20 μm were successfully synthesized for the first time. These crystals exhibited high integrity and optimal afterglow performance, with a duration close to 2 h. The recrystallization-melting method suits industrial production on large scales, and the firing temperature is evidently lowered, which effectively reduces the energy consumption of the synthesis process and significantly improves the long afterglow performance.

Quenching luminescence, thermolysis and SMM behavior of new TbIII, EuIII, GdIII complexes with 4-nitro-N'-(pyridin-2-ylmethylene)benzohydrazide

The reaction of 4-nitro-N'-(pyridin-2-ylmethylene)benzohydrazide (HL) with Ln(OAc)3·4H2O in MeOH makes it possible to synthesize mononuclear complexes [Ln(L)2(OAc)(MeOH)]·2H2O (Ln = TbIII (1), EuIII (2) and GdIII (3)) with chelate acetate and L‒ anions. Compound 1 can be crystallized in reaction with molar ratio HL:Ln = 1:1, 2:1, 3:1, and we successfully synthesized complex with three chelate L anions [Tb(L)3]2·2MeOH·H2O (4) by interaction of TbCl3∙6H2O with deprotonated HL (HL:Ln = 3:1). Terbium(III) compound 1 starts to decompose at ∼323 K and becomes stable up to 552 K according to the STA. Compound 1 shows slow magnetic relaxation with parameters Δeff/kB = (6.75 ± 0.02) K, τ0 = (1.71 × 10−6±1 × 10−8) s. Complexes 1 and 2 exhibit only fluorescence and phosphorescence of the L‒. Ion-centered luminescence of the Tb3+ or Eu3+ ion is not observed. Using the tangent method at the high-energy edge of the phosphorescence spectrum of Gd3+, complex 3 T1 energy level of L‒ is estimated to be 19700 cm−1. Reasons of luminescence quenching are discussed. Structures of 1 and 4 were determined by single crystal X-ray diffraction, and compounds 1–3 were characterized by powder X-ray diffraction (PXRD).

ESI-MS analysis of Cu(I) binding to apo and Zn7 human metallothionein 1A, 2, and 3 identifies the formation of a similar series of metallated species with no individual isoform optimization for Cu(I).

Metallothioneins (MTs) are cysteine-rich proteins involved in metal homeostasis, heavy metal detoxification, and protection against oxidative stress. Whether the four mammalian MT isoforms exhibit different metal binding properties is not clear. In this paper, the Cu(I) binding properties of the apo MT1A, apo MT2, and apo MT3 are compared and the relative Cu(I) binding affinities are reported. In all three isoforms, Cu4, Cu6, and Cu10 species form cooperatively, and MT1A and MT2 also form a Cu13 species. The Cu(I) binding properties of Zn7-MT1A, Zn7-MT2, and Zn7-MT3 are compared systematically using isotopically pure 63Cu(I) and 68Zn(II). The species formed in each MT isoform were detected through electrospray ionization-mass spectrometry and further characterized using room temperature phosphorescence spectroscopy. The mixed metal Cu, Zn species forming in MT1A, MT2, and MT3 have similar stoichiometries and their emission spectral properties indicate that analogous clusters form in the three isoforms. Three parallel metallation pathways have been proposed through analysis of the detailed Cu, Zn speciation in MT1A, MT2, and MT3. Pathway ① results in Cu5Zn5-MT and Cu9Zn3-MT. Pathway ② involves Cu6Zn4-MT and Cu10Zn2-MT. Pathway ③ includes Cu8Zn4-MT. Speciation analysis indicates that Pathway ② is the preferred pathway for MT2. This is also evident in the phosphorescence spectra with the 750nm emission from Cu6Zn4-MT being most prominent in MT2. We see no evidence for different MT isoforms being optimized or exhibiting preferences for certain metals. We discuss the probable stoichiometry for MTs in vivo based on the in vitro determined binding constants.

Design of luminescent complexes with different Cu4I4 cores based on pyridyl phenoxarsines.

A series of luminescent Cu4I4 clusters with stair-step, cubane, and octahedral geometries supported by a novel type of cyclic As,N-ligand, pyridyl-containing 10-phenoxarsines, were synthesized and characterized by NMR spectroscopy, mass spectrometry, elemental analysis, and single-crystal X-ray diffraction analysis. An unusual arrangement of As,N-bidentate and μ2-iodo ligands was found in the octahedral cluster. The structural diversity of the Cu(I) complexes is reflected in their photophysical properties: the phosphorescence spectra of the compounds display emission in a broad spectral range of 495-597 nm. The complex with the Cu4I4L2 stoichiometry bearing a stair-step Cu4I4 core demonstrates temperature-dependent dual emission. The luminescence properties of all complexes were rationalized by DFT calculations.

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.

Structural and photoluminescence properties of lanthanide (III) complexes with carbacylamidophosphate ligand and α,α′-bipyridine

Two series of lanthanide coordination compounds, [Ln(NO3)(L)2(bipy)] and [Ln(L)3(bipy)], where Ln3+ = Eu, Gd, Tb, with the carbacylamidophosphate CAPh ligand N,N,N′,N′-tetraethyl-N″-(trichloroacetyl) phosphoric triamide HL = Cl3CC(O)N(H)P(O)(NEt2)2 and α,α’-bipyridine, were synthesized. The complexes were characterized using infrared, ultraviolet diffuse reflection, and luminescence spectroscopy, as well as elemental and X-ray analyses. The bidentate coordination of the deprotonated CAPh ligand was confirmed through the analysis of the complexes' IR spectra and by X-ray analysis of the bis-CAPh Eu(III) and Tb(III) complexes. The emission and excitation solid-state spectra of the Eu(III) and Tb(III) complexes, as well as the f → f luminescence decay times, were measured at room temperature. Phosphorescence spectra of the Gd(III) complexes were measured at 77 K. The lowest ligands’ triplet state energy depends on the number of coordinated CAPh ligands in the complexes. The Eu(III) and Tb(III) compounds exhibited a strong metal-centered emission with decay times ranging from 1.72 ms to 2.3 ms. Intrinsic quantum yields (QLnLn) equal 82 % for [Eu(NO3)(L)2(bipy)] and 70 % for [Eu(L)3(bipy)]. The Tb(III) complexes revealed a very efficient ligand-to-metal energy transfer at room temperature.

Two distinct mechanisms of flavoprotein spectral tuning revealed by low-temperature and time-dependent spectroscopy.

Flavins such as flavin mononucleotide or flavin adenine dinucleotide are bound by diverse proteins, yet have very similar spectra when in the oxidized state. Recently, we developed new variants of flavin-binding protein CagFbFP exhibiting notable blue (Q148V) or red (I52V A85Q) shifts of fluorescence emission maxima. Here, we use time-resolved and low-temperature spectroscopy to show that whereas the chromophore environment is static in Q148V, an additional protein-flavin hydrogen bond is formed upon photoexcitation in the I52V A85Q variant. Consequently, in Q148V, excitation, emission, and phosphorescence spectra are shifted, whereas in I52V A85Q, excitation and low-temperature phosphorescence spectra are relatively unchanged, while emission spectrum is altered. We also determine the x-ray structures of the two variants to reveal the flavin environment and complement the spectroscopy data. Our findings illustrate two distinct color-tuning mechanisms of flavin-binding proteins and could be helpful for the engineering of new variants with improved optical properties.

Photoinduced transposed Paternò-Büchi reaction for effective synthesis of high-performance jet fuel

High-energy-density fuels are important for volume-limited aerospace vehicles, but the increase of the fuel energy density always leads to poor cryogenic performance. Herein, we investigated the transposed Paternò-Büchi reaction of biomass cyclic ketone and cyclic alkene to synthesize the new kind of alkyl-substituted polycyclic hydrocarbon fuels with high energy density and good cryogenic performance. The triplet-energy-quenching results and phosphorescent emission spectra reveal the sensitization mechanism of the reaction, including photosensitizer excitation, triplet-triplet energy transfer, cyclization and relaxation, and the possible reaction path was revealed by the DFT calculations. The reaction conditions of photosensitizer type and addition, molar ratio of substrates, reaction temperature and incident light intensity were optimized, with the target product yield achieving 65.5%. Moreover, the reaction dynamics of the reaction rate versus the light intensity is established. After hydrogenation deoxygenation reaction, three fuels with high density of 0.864-0.938 g·ml−1 and low freezing point of <−55 °C are obtained. This work provides a benign and effective approach to synthesize high-performance fuels.

Multi‐dimensional stimulus response organic silicone polymer elastomer and its application

AbstractThis work investigated the influence of melamine up to 15 wt% on the stimulation response properties of organic silicone polymer elastomer. The opacity of organic silicone film was attributed to the addition of melamine. For silicone and melamine composite thin films, deformation was increased from 152 to 172%, because the density of NH···O type hydrogen bond decreased the thermal motion of the polymer chain. The thin film of fluorescence and phosphorescence spectra indicated that the maximum luminescence wavelength red‐shifted about 14 nm. The Elastomer with melamine exhibited two‐dimensional stimulus response performance with the change of scale shape‐time‐afterglow emission properties. The phosphorescence of the silicone composite film was derived from the energy donor of melamine. In summary, the study provides detailed guidelines for the preparation of multi‐dimensional organic room temperature phosphorescent elastic materials.

Theoretical and experimental investigation of exciplex-forming and electroluminescent properties of 4-ethyl-3,5-bis[40-(N, N-diphenylamine)biphenyl-4-yl]-4H-1,2,4-triazole

The recently synthesized 4-ethyl-3,5-bis [40-(N, N-diphenylamine)biphenyl-4-yl]-4H-1,2,4-triazole (TPA-TZ) is in this work thoroughly studied as an efficient luminophore with an account of density functional theory. The intense fluorescence is explained as an intramolecular charge-transfer transition from the diphenylamine (donor) moiety to the central part of the dye with a characteristic electron redistribution in the triazole ring (acceptor). The photoluminescence (PL) and phosphorescence (Ph) spectra of TPA-TZ in the film and in THF solution at 77 K were studied together with the well-known 2,4,6-tris [3-(diphenylphosphinyl)phenyl]-1,3,5-triazine (PO-T2T) dye. The latter compound was used as an electron-withdrawing component of the investigated TPA-TZ: PO-T2T exciplex, which is characterized by a relatively high energy level of the excited lowest triplet state. The films of a solid-state mixture of TPA-TZ and PO-T2T showed exciplex-type emission being slightly red-shifted compared to the PL of the individual donor and acceptor compounds. Two OLED devices with emitting layers of TPA-TZ and of the exciplex-forming molecular mixture of TPA-TZ and PO-T2T were prepared. The exciplex–based OLED demonstrated 4 103 cd/m2 brightness, a current efficiency of 22 cd/A, a power efficiency of 6.77 lm/W, and an external quantum efficiency (EQE) of 7%. This confirms the possibility of triplet harvesting in the molecular mixture of TPA-TZ and PO-T2T, since the theoretical EQE limit for OLED based on the prompt fluorescence is 5%.

Synthesis and properties of long-lived room-temperature phosphorescent liquid crystal polymers based on “Jacketing” effect

Polymerization is one of the most widely used strategies to achiever RTP. To date, various polymer-based RTP materials have been reported. However, how to improve the phosphorescence lifetime of polymer-based RTP materials still needs to be further researched. In this article, we proposed a new strategy to realize long-lived room-temperature phosphorescence by utilizing the “jacketing” effect of mesogen-jacketed liquid crystal polymers. Two polymers PMJ0DFM and PMJ6DFM with different flexible spacer length were synthesized, and their liquid crystal phase structures and photo-physical properties were systematically investigated. PMJ0DFM formed columnar nematic phase while PMJ6DFM formed a more ordered hexagonal columnar phase liquid crystal. For PMJ0DFM without spacer length, due to the strong “Jacketing” effect, the thermal motion of the chromophore was suppressed, and it was also more conducive to the aggregation and planarization of the chromophores. Therefore, PMJ0DFM film showed longer phosphorescence lifetime and more red-shifted phosphorescence spectrum than PMJ6DFM film. The phosphorescence lifetimes of PMJ0DFM and PMJ6DFM were 355 ms and 247 ms, respectively. In addition, we also explored their application in linearly polarized luminescent materials. When oriented, PMJ0DFM and PMJ6DFM film could emit efficient linearly polarized room temperature phosphorescence.

Triplet state spectroscopy reveals involvement of the buried tryptophan residue 310 in Glyceraldehyde-3-phosphate dehydrogenase (GAPD) in the interaction with acrylamide

Using conventional steady state and time resolved fluorescence study of the interaction between a multi-tryptophan protein and a quencher, it is difficult, if not impossible to identify the particular tryptophan residue/residues involved in the interaction. In this work we have exemplified the above contention using a multi-tryptophan protein, Glyceraldehyde-3-phosphate dehydrogenase (GAPD) from rabbit muscle having three tryptophan (Trp) residues at positions 84, 193 and 310 and a neutral quencher acrylamide in Tris buffer of pH 7.5. From the steady state and time resolved fluorescence quenching (at 298 K) with acrylamide Ksv, K and kq for the system have been calculated. Low temperature phosphorescence (LTP) spectra at 77 K of GAPD in suitable cryosolvent is known to exhibit two (0,0) bands corresponding to two tryptophan residues 193 and 310. Using the LTP study of free GAPD and GAPD – acrylamide it is possible to identify that the buried Trp 310 residue is specifically involved in the interaction with acrylamide. This is possible without doing any site-directed mutagenesis of GAPD which contains Trp residues at 84, 193 and 310. Tyrosine 320 is also specifically quenched. The results have been corroborated using the molecular docking studies. Molecular Dynamics simulation supports our contention of the involvement of Trp 310 and also shows that the other nearest residues of acrylamide are Val175 and Val232.

A Ruthenium(II) complex based long lifetime phosphorescent probe for copper ions and pH detection

ObjectiveTransition metal ruthenium(II) complex was used to prepare a dual-functional phosphorescent probe for the detection of Cu2+ ion and pH. MethodsThe ligand (E)-6-((thiazol-2-yl methylene)amino)-1,10-phenanthrolin-5-amine (tmpa) was prepared by condensation of 5,6-diamine-1, 10-phenanthroline with 2-formylthiazole, and then ruthenium(II) complex [Ru(bpy)2tmpa](PF6) (Ru-tmpa, bpy ​= ​2,2′-bipyridine) was synthesized by the coordination of tmpa with cis-Ru(bpy)2Cl2. Phosphorescence spectra were measured to investigate its response to metal ions (Li+, Na+, K+, Mg2+, Ca2+, Mn2+, Pb2+, Cr2+, Co2+, Ni2+, Cu+, Cu2+, Fe3+, Fe2+ and Zn2+). The binding affinity and detecting limit of Ru-tmpa to copper ions were tested by titration experiment. The ability of the probe to monitor copper ion levels inside cells was tested by confocal microscopy imaging. ResultsRu-tmpa can rapidly, sensitively and selectively detect Cu2+ in water and biological sample, and shows a sensitive phosphorescence response to pH. Ru-tmpa can penetrate cell membrane, enter the cell, and monitor the level of copper ions inside cell. ConclusionA novel fluorescent probe Ru-tmpa was synthesized to provide a powerful tool for the detection of Cu2+ and pH in biological and environmental systems.

Temperature Dependence of the Luminescence Spectra of Copper(II) Mesoporphyrinate in a Polystyrene Film and on the Surface of Microparticles of Al2O3

Copper(II) diethyl mesoporphyrinate (CuMP), as well as luminescent materials based on it, namely, films of CuMP in polystyrene and microparticles of aluminum oxide covered by a layer of CuMP, is obtained. An analysis of the change in the photoluminescence spectra of the new materials in a range of temperatures of 77–298 K is conducted. It is found that, upon varying temperature in the photoluminescence spectra of CuMP in polystyrene, the ratio of the intensities of phosphorescence from the triplet electron levels 2T1 and 4T1 changes and a shift of the spectra according to the Stokes law is observed. A change in the ratio of the intensities of emission from the levels 2T1 and 4T1 is also observed in the luminescence spectra of CuMP adsorbed on the surface of microparticles of Al2O3 upon varying temperature; however, an anti-Stokes shift of phosphorescence from the level 2T1 is observed at the same time. An analysis of the kinetics of decay of the phosphorescence spectra of the CuMP dye in composite materials that possess the properties of luminescent temperature sensors is conducted.