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In lanthanide-doped upconversion nanoparticles (UCNPs), the concentration of emitter ions, also known as activator ions, is usually limited to 1 - 5 mol% due to concentration quenching effects. This circumstance limits the luminescent efficiency of UCNPs' and their use in a variety of application areas. Earlier studies have attributed the activator concentration quenching to migration of energy to the nanoparticle surface, while indicating that cross-relaxation between activator ions had a minor role therein. In this work, we carried out comparative studies on Er3+-doped and Yb3+-Er3+ codoped UCNPs and could, in contrast to this notion, prove a general adverse effect of cross-relaxation between activator ions, here Er3+ ions, on up -conversion luminescence (UCL). The direct result of the cross-relaxation is that the energy of the excitation light is accumulated into a low-lying excited state of Er3+ in the infrared region, so forming a "low-lying excited state energy trap ". As a result, the excitation energy is used for generating down-conversion lu-minescence or for indirectly facilitating UCL channels that are directly related to the low-lying excited state energy trap. The identified effect can be used to regulate UCL channels to achieve a concentrated UCL band that is more favorable for certain applications, e.g., biological imaging., QC 20230131

Lanthanide-doped upconversion nanoparticles (UCNPs) have been widely exploited as nanoprobes or energy transducers in traditional as well as emerging biological applications, such as bioimaging, photodynamic ther-apy, optogenetics, gene editing. However, the breadth and depth of their utility in the biomedical areas are still not comparable to conventional luminescent probes, such as fluorescent dyes and semiconductor quantum dots. Their application is largely limited by their large size, typically > 20 nm, to ensure a sufficient luminescence brightness. In order to enhance the brightness of UCNPs without exceeding the critical size limitations for biomedical applications, we employ here a transient energy trapping effect as a nanoprobe surface passivation strategy to prevent deleterious distant energy migration in the host lattice, which is particularly prevalent in ultrasmall UCNPs and leads to luminescence quenching. We demonstrate this strategy by incorporating Tm3+ ions as energy trapping centers near the surface of sub-10 nm NaYF4: Yb, Er UCNPs and obtain an emission enhancement by almost one order of magnitude without any increment on the nanoparticle size. Our work presents a promising strategy for the preparation of ultrasmall and bright upconversion nanoprobes that are less vulnerable to surface quenching and that potentially minimize the interference with the object. This facilitates their biomedical applications as here demonstrated by unprecedented high-quality cell labeling and imaging, featured with very uniform nanoparticle distribution in the outer nuclear region., QC 20230118

Dual-ionic pyrazolium salts have in this work been synthesized and shown to catalyze the coupling reaction of carbon dioxide (CO2) with epichlorohydrin achieving a 90% yield under 30 °C and 0.1 MPa CO2 pressure. With the aid of a small amount of water, the product yield is greatly improved up to 99.5% under the same reaction conditions, which corresponds to a rate enhancement of up to 1.4 times for the formation of the carbonate. We propose and explore a dual origin of the role of water, first by affecting the gas to liquid mass transfer of CO2, and second a mechanism where water triggers a proton transfer that in turn underlies efficient conversion of CO2. This theoretically derived mechanism is also confirmed by 13C NMR and FT-IR spectroscopy results. The catalyst was found to be reusable eight times without obvious reduction of catalytic activity. The finding presented that an already efficient reaction to attract CO2 is further greatly promoted only by the addition of water which can have important ramifications for green technology., QC 20230707

Lanthanide upconversion nanoparticles (UCNPs) have beenextensivelyexplored as biomarkers, energy transducers, and information carriersin wide-ranging applications in areas from healthcare and energy toinformation technology. In promoting the brightness and enrichingthe functionalities of UCNPs, core-shell structural engineeringhas been well-established as an important approach. Despite its importance,a strong limiting issue has been identified, namely, cation intermixingin the interfacial region of the synthesized core-shell nanoparticles.Currently, there still exists confusion regarding this destructivephenomenon and there is a lack of facile means to reach a delicatecontrol of it. By means of a new set of experiments, we identify andprovide in this work a comprehensive picture for the major physicalmechanism of cation intermixing occurring in synthesis of core-shellUCNPs, i.e., partial or substantial core nanoparticle dissolutionfollowed by epitaxial growth of the outer layer and ripening of theentire particle. Based on this picture, we provide an easy but effectiveapproach to tackle this issue that enables us to produce UCNPs withhighly boosted optical properties., QC 20230824

Cyclo[n]carbons (n = 5, 7, 9,..., 29) composed from an odd number of carbon atoms are studied computationally at density functional theory (DFT) and ab initio complete active space self-consistent field (CASSCF) levels of theory to get insight into their electronic structure and aromaticity. DFT calculations predict a strongly delocalized carbene structure of the cyclo[n]carbons and an aromatic character for all of them. In contrast, calculations at the CASSCF level yield geometrically bent and electronically localized carbene structures leading to an alternating double aromaticity of the odd-number cyclo[n]carbons. CASSCF calculations yield a singlet electronic ground state for the studied cyclo[n]carbons except for C25, whereas at the DFT level the energy difference between the lowest singlet and triplet states depends on the employed functional. The BHandHLYP functional predicts a triplet ground state of the larger odd-number cyclo[n]carbons starting from n = 13. Current-density calculations at the BHandHLYP level using the CASSCFoptimized molecular structures show that there is a through-space delocalization in the cyclo[n]carbons. The current density avoids the carbene carbon atom, leading to an alternating double aromaticity of the oddnumber cyclo[n]carbons satisfying the antiaromatic [4k+1] and aromatic [4k+3] rules. C11, C15, and C19 are aromatic and can be prioritized in future synthesis. We predict a bond-shift phenomenon for the triplet state of the cyclo[n]carbons leading to resonance structures that have different reactivity toward dimerization.

Cyclo[n]carbons (n = 5, 7, 9,..., 29) composed from an odd number of carbon atoms are studied computationally at density functional theory (DFT) and ab initio complete active space self-consistent field (CASSCF) levels of theory to get insight into their electronic structure and aromaticity. DFT calculations predict a strongly delocalized carbene structure of the cyclo[n]carbons and an aromatic character for all of them. In contrast, calculations at the CASSCF level yield geometrically bent and electronically localized carbene structures leading to an alternating double aromaticity of the odd-number cyclo[n]carbons. CASSCF calculations yield a singlet electronic ground state for the studied cyclo[n]carbons except for C25, whereas at the DFT level the energy difference between the lowest singlet and triplet states depends on the employed functional. The BHandHLYP functional predicts a triplet ground state of the larger odd-number cyclo[n]carbons starting from n = 13. Current-density calculations at the BHandHLYP level using the CASSCFoptimized molecular structures show that there is a through-space delocalization in the cyclo[n]carbons. The current density avoids the carbene carbon atom, leading to an alternating double aromaticity of the oddnumber cyclo[n]carbons satisfying the antiaromatic [4k+1] and aromatic [4k+3] rules. C11, C15, and C19 are aromatic and can be prioritized in future synthesis. We predict a bond-shift phenomenon for the triplet state of the cyclo[n]carbons leading to resonance structures that have different reactivity toward dimerization., Funding Agencies|Swedish Research Council [2020-04600]; Academy of Finland [325369, 314821]; Danish Council for Independent Research [DFF4181-00206, 9040-00265]; VILLUM FONDEN [40871]; Russian Scientific Foundation [18-19-00268-Pi]

Cyclo[n]carbons (n = 5, 7, 9,..., 29) composed from an odd number of carbon atoms are studied computationally at density functional theory (DFT) and ab initio complete active space self-consistent field (CASSCF) levels of theory to get insight into their electronic structure and aromaticity. DFT calculations predict a strongly delocalized carbene structure of the cyclo[n]carbons and an aromatic character for all of them. In contrast, calculations at the CASSCF level yield geometrically bent and electronically localized carbene structures leading to an alternating double aromaticity of the odd-number cyclo[n]carbons. CASSCF calculations yield a singlet electronic ground state for the studied cyclo[n]carbons except for C25, whereas at the DFT level the energy difference between the lowest singlet and triplet states depends on the employed functional. The BHandHLYP functional predicts a triplet ground state of the larger odd-number cyclo[n]carbons starting from n = 13. Current-density calculations at the BHandHLYP level using the CASSCFoptimized molecular structures show that there is a through-space delocalization in the cyclo[n]carbons. The current density avoids the carbene carbon atom, leading to an alternating double aromaticity of the oddnumber cyclo[n]carbons satisfying the antiaromatic [4k+1] and aromatic [4k+3] rules. C11, C15, and C19 are aromatic and can be prioritized in future synthesis. We predict a bond-shift phenomenon for the triplet state of the cyclo[n]carbons leading to resonance structures that have different reactivity toward dimerization.

Cyclo[n]carbons (n = 5, 7, 9,..., 29) composed from an odd number of carbon atoms are studied computationally at density functional theory (DFT) and ab initio complete active space self-consistent field (CASSCF) levels of theory to get insight into their electronic structure and aromaticity. DFT calculations predict a strongly delocalized carbene structure of the cyclo[n]carbons and an aromatic character for all of them. In contrast, calculations at the CASSCF level yield geometrically bent and electronically localized carbene structures leading to an alternating double aromaticity of the odd-number cyclo[n]carbons. CASSCF calculations yield a singlet electronic ground state for the studied cyclo[n]carbons except for C25, whereas at the DFT level the energy difference between the lowest singlet and triplet states depends on the employed functional. The BHandHLYP functional predicts a triplet ground state of the larger odd-number cyclo[n]carbons starting from n = 13. Current-density calculations at the BHandHLYP level using the CASSCFoptimized molecular structures show that there is a through-space delocalization in the cyclo[n]carbons. The current density avoids the carbene carbon atom, leading to an alternating double aromaticity of the oddnumber cyclo[n]carbons satisfying the antiaromatic [4k+1] and aromatic [4k+3] rules. C11, C15, and C19 are aromatic and can be prioritized in future synthesis. We predict a bond-shift phenomenon for the triplet state of the cyclo[n]carbons leading to resonance structures that have different reactivity toward dimerization.

Cyclo[n]carbons (n = 5, 7, 9,..., 29) composed from an odd number of carbon atoms are studied computationally at density functional theory (DFT) and ab initio complete active space self-consistent field (CASSCF) levels of theory to get insight into their electronic structure and aromaticity. DFT calculations predict a strongly delocalized carbene structure of the cyclo[n]carbons and an aromatic character for all of them. In contrast, calculations at the CASSCF level yield geometrically bent and electronically localized carbene structures leading to an alternating double aromaticity of the odd-number cyclo[n]carbons. CASSCF calculations yield a singlet electronic ground state for the studied cyclo[n]carbons except for C25, whereas at the DFT level the energy difference between the lowest singlet and triplet states depends on the employed functional. The BHandHLYP functional predicts a triplet ground state of the larger odd-number cyclo[n]carbons starting from n = 13. Current-density calculations at the BHandHLYP level using the CASSCFoptimized molecular structures show that there is a through-space delocalization in the cyclo[n]carbons. The current density avoids the carbene carbon atom, leading to an alternating double aromaticity of the oddnumber cyclo[n]carbons satisfying the antiaromatic [4k+1] and aromatic [4k+3] rules. C11, C15, and C19 are aromatic and can be prioritized in future synthesis. We predict a bond-shift phenomenon for the triplet state of the cyclo[n]carbons leading to resonance structures that have different reactivity toward dimerization., Funding Agencies|Swedish Research Council [2020-04600]; Academy of Finland [325369, 314821]; Danish Council for Independent Research [DFF4181-00206, 9040-00265]; VILLUM FONDEN [40871]; Russian Scientific Foundation [18-19-00268-Pi]

Cyclo[n]carbons (n = 5, 7, 9,..., 29) composed from an odd number of carbon atoms are studied computationally at density functional theory (DFT) and ab initio complete active space self-consistent field (CASSCF) levels of theory to get insight into their electronic structure and aromaticity. DFT calculations predict a strongly delocalized carbene structure of the cyclo[n]carbons and an aromatic character for all of them. In contrast, calculations at the CASSCF level yield geometrically bent and electronically localized carbene structures leading to an alternating double aromaticity of the odd-number cyclo[n]carbons. CASSCF calculations yield a singlet electronic ground state for the studied cyclo[n]carbons except for C25, whereas at the DFT level the energy difference between the lowest singlet and triplet states depends on the employed functional. The BHandHLYP functional predicts a triplet ground state of the larger odd-number cyclo[n]carbons starting from n = 13. Current-density calculations at the BHandHLYP level using the CASSCFoptimized molecular structures show that there is a through-space delocalization in the cyclo[n]carbons. The current density avoids the carbene carbon atom, leading to an alternating double aromaticity of the oddnumber cyclo[n]carbons satisfying the antiaromatic [4k+1] and aromatic [4k+3] rules. C11, C15, and C19 are aromatic and can be prioritized in future synthesis. We predict a bond-shift phenomenon for the triplet state of the cyclo[n]carbons leading to resonance structures that have different reactivity toward dimerization.

Cyclo[n]carbons (n = 5, 7, 9,..., 29) composed from an odd number of carbon atoms are studied computationally at density functional theory (DFT) and ab initio complete active space self-consistent field (CASSCF) levels of theory to get insight into their electronic structure and aromaticity. DFT calculations predict a strongly delocalized carbene structure of the cyclo[n]carbons and an aromatic character for all of them. In contrast, calculations at the CASSCF level yield geometrically bent and electronically localized carbene structures leading to an alternating double aromaticity of the odd-number cyclo[n]carbons. CASSCF calculations yield a singlet electronic ground state for the studied cyclo[n]carbons except for C25, whereas at the DFT level the energy difference between the lowest singlet and triplet states depends on the employed functional. The BHandHLYP functional predicts a triplet ground state of the larger odd-number cyclo[n]carbons starting from n = 13. Current-density calculations at the BHandHLYP level using the CASSCFoptimized molecular structures show that there is a through-space delocalization in the cyclo[n]carbons. The current density avoids the carbene carbon atom, leading to an alternating double aromaticity of the oddnumber cyclo[n]carbons satisfying the antiaromatic [4k+1] and aromatic [4k+3] rules. C11, C15, and C19 are aromatic and can be prioritized in future synthesis. We predict a bond-shift phenomenon for the triplet state of the cyclo[n]carbons leading to resonance structures that have different reactivity toward dimerization., Funding Agencies|Swedish Research Council [2020-04600]; Academy of Finland [325369, 314821]; Danish Council for Independent Research [DFF4181-00206, 9040-00265]; VILLUM FONDEN [40871]; Russian Scientific Foundation [18-19-00268-Pi]

Cyclo[n]carbons (n = 5, 7, 9,..., 29) composed from an odd number of carbon atoms are studied computationally at density functional theory (DFT) and ab initio complete active space self-consistent field (CASSCF) levels of theory to get insight into their electronic structure and aromaticity. DFT calculations predict a strongly delocalized carbene structure of the cyclo[n]carbons and an aromatic character for all of them. In contrast, calculations at the CASSCF level yield geometrically bent and electronically localized carbene structures leading to an alternating double aromaticity of the odd-number cyclo[n]carbons. CASSCF calculations yield a singlet electronic ground state for the studied cyclo[n]carbons except for C25, whereas at the DFT level the energy difference between the lowest singlet and triplet states depends on the employed functional. The BHandHLYP functional predicts a triplet ground state of the larger odd-number cyclo[n]carbons starting from n = 13. Current-density calculations at the BHandHLYP level using the CASSCFoptimized molecular structures show that there is a through-space delocalization in the cyclo[n]carbons. The current density avoids the carbene carbon atom, leading to an alternating double aromaticity of the oddnumber cyclo[n]carbons satisfying the antiaromatic [4k+1] and aromatic [4k+3] rules. C11, C15, and C19 are aromatic and can be prioritized in future synthesis. We predict a bond-shift phenomenon for the triplet state of the cyclo[n]carbons leading to resonance structures that have different reactivity toward dimerization.

Cyclo[n]carbons (n = 5, 7, 9,..., 29) composed from an odd number of carbon atoms are studied computationally at density functional theory (DFT) and ab initio complete active space self-consistent field (CASSCF) levels of theory to get insight into their electronic structure and aromaticity. DFT calculations predict a strongly delocalized carbene structure of the cyclo[n]carbons and an aromatic character for all of them. In contrast, calculations at the CASSCF level yield geometrically bent and electronically localized carbene structures leading to an alternating double aromaticity of the odd-number cyclo[n]carbons. CASSCF calculations yield a singlet electronic ground state for the studied cyclo[n]carbons except for C25, whereas at the DFT level the energy difference between the lowest singlet and triplet states depends on the employed functional. The BHandHLYP functional predicts a triplet ground state of the larger odd-number cyclo[n]carbons starting from n = 13. Current-density calculations at the BHandHLYP level using the CASSCFoptimized molecular structures show that there is a through-space delocalization in the cyclo[n]carbons. The current density avoids the carbene carbon atom, leading to an alternating double aromaticity of the oddnumber cyclo[n]carbons satisfying the antiaromatic [4k+1] and aromatic [4k+3] rules. C11, C15, and C19 are aromatic and can be prioritized in future synthesis. We predict a bond-shift phenomenon for the triplet state of the cyclo[n]carbons leading to resonance structures that have different reactivity toward dimerization., Funding Agencies|Swedish Research Council [2020-04600]; Academy of Finland [325369, 314821]; Danish Council for Independent Research [DFF4181-00206, 9040-00265]; VILLUM FONDEN [40871]; Russian Scientific Foundation [18-19-00268-Pi]

Cyclo[n]carbons (n = 5, 7, 9,..., 29) composed from an odd number of carbon atoms are studied computationally at density functional theory (DFT) and ab initio complete active space self-consistent field (CASSCF) levels of theory to get insight into their electronic structure and aromaticity. DFT calculations predict a strongly delocalized carbene structure of the cyclo[n]carbons and an aromatic character for all of them. In contrast, calculations at the CASSCF level yield geometrically bent and electronically localized carbene structures leading to an alternating double aromaticity of the odd-number cyclo[n]carbons. CASSCF calculations yield a singlet electronic ground state for the studied cyclo[n]carbons except for C25, whereas at the DFT level the energy difference between the lowest singlet and triplet states depends on the employed functional. The BHandHLYP functional predicts a triplet ground state of the larger odd-number cyclo[n]carbons starting from n = 13. Current-density calculations at the BHandHLYP level using the CASSCFoptimized molecular structures show that there is a through-space delocalization in the cyclo[n]carbons. The current density avoids the carbene carbon atom, leading to an alternating double aromaticity of the oddnumber cyclo[n]carbons satisfying the antiaromatic [4k+1] and aromatic [4k+3] rules. C11, C15, and C19 are aromatic and can be prioritized in future synthesis. We predict a bond-shift phenomenon for the triplet state of the cyclo[n]carbons leading to resonance structures that have different reactivity toward dimerization.

Cyclo[n]carbons (n = 5, 7, 9,..., 29) composed from an odd number of carbon atoms are studied computationally at density functional theory (DFT) and ab initio complete active space self-consistent field (CASSCF) levels of theory to get insight into their electronic structure and aromaticity. DFT calculations predict a strongly delocalized carbene structure of the cyclo[n]carbons and an aromatic character for all of them. In contrast, calculations at the CASSCF level yield geometrically bent and electronically localized carbene structures leading to an alternating double aromaticity of the odd-number cyclo[n]carbons. CASSCF calculations yield a singlet electronic ground state for the studied cyclo[n]carbons except for C25, whereas at the DFT level the energy difference between the lowest singlet and triplet states depends on the employed functional. The BHandHLYP functional predicts a triplet ground state of the larger odd-number cyclo[n]carbons starting from n = 13. Current-density calculations at the BHandHLYP level using the CASSCFoptimized molecular structures show that there is a through-space delocalization in the cyclo[n]carbons. The current density avoids the carbene carbon atom, leading to an alternating double aromaticity of the oddnumber cyclo[n]carbons satisfying the antiaromatic [4k+1] and aromatic [4k+3] rules. C11, C15, and C19 are aromatic and can be prioritized in future synthesis. We predict a bond-shift phenomenon for the triplet state of the cyclo[n]carbons leading to resonance structures that have different reactivity toward dimerization., Funding Agencies|Swedish Research Council [2020-04600]; Academy of Finland [325369, 314821]; Danish Council for Independent Research [DFF4181-00206, 9040-00265]; VILLUM FONDEN [40871]; Russian Scientific Foundation [18-19-00268-Pi]

Cyclo[n]carbons (n = 5, 7, 9,..., 29) composed from an odd number of carbon atoms are studied computationally at density functional theory (DFT) and ab initio complete active space self-consistent field (CASSCF) levels of theory to get insight into their electronic structure and aromaticity. DFT calculations predict a strongly delocalized carbene structure of the cyclo[n]carbons and an aromatic character for all of them. In contrast, calculations at the CASSCF level yield geometrically bent and electronically localized carbene structures leading to an alternating double aromaticity of the odd-number cyclo[n]carbons. CASSCF calculations yield a singlet electronic ground state for the studied cyclo[n]carbons except for C25, whereas at the DFT level the energy difference between the lowest singlet and triplet states depends on the employed functional. The BHandHLYP functional predicts a triplet ground state of the larger odd-number cyclo[n]carbons starting from n = 13. Current-density calculations at the BHandHLYP level using the CASSCFoptimized molecular structures show that there is a through-space delocalization in the cyclo[n]carbons. The current density avoids the carbene carbon atom, leading to an alternating double aromaticity of the oddnumber cyclo[n]carbons satisfying the antiaromatic [4k+1] and aromatic [4k+3] rules. C11, C15, and C19 are aromatic and can be prioritized in future synthesis. We predict a bond-shift phenomenon for the triplet state of the cyclo[n]carbons leading to resonance structures that have different reactivity toward dimerization.

Upconversion (UC) technology makes it possible to harvest infrared (IR) light from the sun and has increasingly been employed in recent years to improve the efficiency of solar cells. The progress in the area concerns both research on fundamental principles and processes of UC and technologies of device fabrication. Significant increase of important solar cell parameters, like short-circuit photocurrent density and open-circuit photovoltage as well as the total photon-to-current efficiency, has been accomplished. We here review the research published during the last few years in the area, in particular we consider the two most cherished techniques, namely the incorporation of upconverting nanophosphors directly into the photoanodes of the solar cells and the introduction of plasmonic metal nanoparticles co-existing with the UC particles. Other ways to achieve strong field enhancement, and the use of the non-linear nature of UC, is to apply microlenses, with or without assisting plasmonic excitation. Further enhanced UC action has been demonstrated by broad band and effective harvesting by organic IR antennas, with subsequent mediation by an intermediate nanoshell of the energy into the upconverting core. Codoping, nanohybrid and layer-by-layer technologies involving upconverting particles as well as the use of upconverting nanoparticles in hole-transport and electrolyte layers, tested in recent works, are also reviewed. While most of these technologies employ upconverting rare earth metals for sequential photon absorption, the main alternative technique, namely triplet-triplet annihilation UC using organic materials, is also reviewed. It is our belief that all these approaches will be further much researched in the near future, with potentially great impact on solar cell technology.

The equilibrium structures and vibrational frequencies of the ground state and several singlet low-lying excited states of alpha-and beta-protonated naphthalenes (alpha-and beta-HN+) have been studied by time -dependent density -functional theory (TD-DFT). Within the Franck -Condon approximation, vibronic absorption spectra of alpha-HN+ and beta-HN+, together with the vibronic emission spectrum of alpha-HN+, have been calculated. The obtained good agreement between the theoretical and experimental spectra enables to correctly assign vibronic features in both absorption and emission spectra. Moreover, the non -radiative deactivation pathway from the low-lying excite states to the ground state in alpha-HN+ and beta-HN+, as well as the photo-induce proton transfer pathway, are investigated at the CASPT2/CASSCF/6-31G* level. Our study is helpful for understanding the photochemical behavior of these important polycyclic aromatic hydrocarbon molecules., QC 20181015

The mechanism of CO2 fixation catalyzed by protic hydroxyl-functionalized quaternary ammonium ionic liquids (ILs) is investigated by two different models, the Single-IL model and the Double-IL model. The relative sequence of catalytic activity calculated by the Single-IL model is contradictory with the experimental result. The situation is totally varied when the Double-IL model is utilized. In this system, ILs are not limited to the catalyst but solvent. The ILs are incorporated into the catalytic system to consider the solvent effect rather than by the existing solvent model. When the solvent effect is included, it is better to distinguish the catalytic activity of three ILs. According to the noncovalent interaction and the atoms in molecules analysis, the highest catalytic activity of tris(2-hydroxyethyl)ammonium bromide ([HTEA]Br) is attributed to its strongest nucleophilic attack and moderate hydrogen bond interaction between IL and reactant. It is necessary to consider the interaction between ILs to get a reliable result. Moreover, the solvent effect aroused by ILs should be carefully considered., QC 20180619

A new Ir(III) complex (dfpypya)(2)Ir(pic-OH) (2) is theoretically designed by introduction of a simple hydroxyl group into the ancillary ligand on the basis of (dfpypya)(2)Ir(pic) (1) with the aim to get the high efficiency and stable blue-emitting phosphors, where dfpypya is 3-methyl-6-(2',4'-difluoro-pyridinato)pyridazine, pic is picolinate, and pic OH is 3-hydroxypicolinic acid. The other configuration (dfpypya)(2)Ir(pic OH)' (3) is also investigated to compare with 2. The difference between 2 and 3 is whether the intramolecular hydrogen bond is formed in the (dfpypya)(2)Ir(pic OH). The quantum yield is determined by three different methods including the semiquantitative and quantitative methods. To quantitatively determine the quantum yield is still not an easy task to be completed. This work would provide some useful advices to select the suitable method to reliably evaluate the quantum yield. Complex 2 has larger quantum yield and more stability as compared with 1 and 3. The formation of intramolecular hydrogen bond would become a new method to design new phosphor with the desired properties., QC 20170929

QC 20180118