New tetracyanidoborate salts with hydrated rare‐earth‐metal cations (RE3+) were synthesized by the reactions of rare‐earth‐metal oxides or hydroxides with tetracyanidoboronic acid, HB(CN)4·nH2O. Two ...groups of isostructural compounds were obtained with the formulas RE(H2O)8B(CN)43·nH2O (structure I) and RE(H2O)7{κ1N‐B(CN)4}B(CN)42 (structure II) for RE = Y, Tb, Dy, Ho, Er, Tm, Yb, and Lu and n ≤ 3. Both structures have discrete eight‐coordinate RE3+ complex cations, as RE(H2O)83+ in structure I and RE(H2O)7{κ1N‐B(CN)4}2+ in structure II. The heating of the compounds to temperature of ca. 160 °C gives anhydrous samples, but elongated heating to temperatures above ca. 200 °C leads to the slow decomposition of the tetracyanidoborates. The luminescence properties of a solid sample of the anhydrous Tb salt and a solution of the Dy salt were investigated. Both show intense lines in their excitation and emission spectra that were assigned to electronic transitions within the f and d shells.
The structural features and properties, including luminescence, of the rare‐earth tetracyanidoborate salts RE(H2O)8B(CN)43·nH2O and RE(H2O)7{κ1N‐B(CN)4}B(CN)42 (RE = Y, Tb, Dy, Ho, Er, Tm, Yb, Lu; n ≤ 3) are investigated.
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•The impact of dynamic spectral shifts on transient spectra is analyzed.•Global analysis results are compared to a Taylor expansion of the spectrum.•An interpretation of time ...constants and decay associated spectra is given.•With this the shift dynamics can be extracted from the global analysis parameters.•The obtained insights are applied to the solvation dynamics of Coumarin 152.
Time dependent spectral shifts caused by energetic relaxation processes frequently contribute to time resolved spectral data. They make a global analysis of transient spectra challenging, since the basic assumption of separability of time and frequency dependence does not hold. We compare the global analysis results of synthetic transient spectra to a Taylor expansion of their spectral shape at infinite time. Thereby we can elucidate the correlation of time constants and decay associated spectra resulting from global analysis with the underlying shift dynamics. The obtained insights are applied to transient absorption spectra of Coumarin 152 and its solvation dynamics.
Polymer micelles are an attractive means to solubilize water insoluble compounds such as drugs. Drug loading, formulations stability and control over drug release are crucial factors for drug‐loaded ...polymer micelles. The interactions between the polymeric host and the guest molecules are considered critical to control these factors but typically barely understood. Here, we compare two isomeric polymer micelles, one of which enables ultra‐high curcumin loading exceeding 50 wt.%, while the other allows a drug loading of only 25 wt.%. In the low capacity micelles, steady‐state fluorescence revealed a very unusual feature of curcumin fluorescence, a high energy emission at 510 nm. Time‐resolved fluorescence upconversion showed that the fluorescence life time of the corresponding species is too short in the high‐capacity micelles, preventing an observable emission in steady‐state. Therefore, contrary to common perception, stronger interactions between host and guest can be detrimental to the drug loading in polymer micelles.
Don't come too close! Two isomeric triblock copolymers show differences in their interaction with curcumin. Unexpectedly, the polymer that leaves curcumin more freedom allows for much higher drug loading while the one that binds more tightly can incorporate much less drug.
New tetracyanidoborate salts with hydrated rare-earth-metal cations (RE super(3+)) were synthesized by the reactions of rare-earth-metal oxides or hydroxides with tetracyanidoboronic acid, HB(CN) ...sub(4).nH sub(2)O. Two groups of isostructural compounds were obtained with the formulas RE(H sub(2)O) sub(8)B(CN) sub(4) sub(3).nH sub(2)O (structure I) and RE(H sub(2)O) sub(7){ Kappa super(1)N-B(CN) sub(4)}B(CN) sub(4) sub(2) (structure II) for RE = Y, Tb, Dy, Ho, Er, Tm, Yb, and Lu and n less than or equal to 3. Both structures have discrete eight-coordinate RE super(3+) complex cations, as RE(H sub(2)O) sub(8) super(3+) in structure I and RE(H sub(2)O) sub(7){ Kappa super(1)N-B(CN) sub(4)} super(2+) in structure II. The heating of the compounds to temperature of ca. 160 degree C gives anhydrous samples, but elongated heating to temperatures above ca. 200 degree C leads to the slow decomposition of the tetracyanidoborates. The luminescence properties of a solid sample of the anhydrous Tb salt and a solution of the Dy salt were investigated. Both show intense lines in their excitation and emission spectra that were assigned to electronic transitions within the f and d shells. The structural features and properties, including luminescence, of the rare-earth tetracyanidoborate salts RE(H sub(2)O) sub(8)B(CN) sub(4) sub(3).nH sub(2)O and RE(H sub(2)O) sub(7){ Kappa super(1)N-B(CN) sub(4)}B(CN) sub(4) sub(2) (RE = Y, Tb, Dy, Ho, Er, Tm, Yb, Lu; n less than or equal to 3) are investigated.
Abstract
New tetracyanidoborate salts with hydrated rare‐earth‐metal cations (
RE
3+
) were synthesized by the reactions of rare‐earth‐metal oxides or hydroxides with tetracyanidoboronic acid, HB(CN)
...4
·
n
H
2
O. Two groups of isostructural compounds were obtained with the formulas
RE
(H
2
O)
8
B(CN)
4
3
·
n
H
2
O (structure I) and
RE
(H
2
O)
7
{κ
1
N
‐B(CN)
4
}B(CN)
4
2
(structure II) for
RE
= Y, Tb, Dy, Ho, Er, Tm, Yb, and Lu and
n
≤ 3. Both structures have discrete eight‐coordinate
RE
3+
complex cations, as
RE
(H
2
O)
8
3+
in structure I and
RE
(H
2
O)
7
{κ
1
N
‐B(CN)
4
}
2+
in structure II. The heating of the compounds to temperature of ca. 160 °C gives anhydrous samples, but elongated heating to temperatures above ca. 200 °C leads to the slow decomposition of the tetracyanidoborates. The luminescence properties of a solid sample of the anhydrous Tb salt and a solution of the Dy salt were investigated. Both show intense lines in their excitation and emission spectra that were assigned to electronic transitions within the f and d shells.
New tetracyanidoborate salts with hydrated rare-earth-metal cations (RE3+) were synthesized by the reactions of rare-earth-metal oxides or hydroxides with tetracyanidoboronic acid, HB(CN)4·nH2O. Two ...groups of isostructural compounds were obtained with the formulas RE(H2O)8B(CN)43·nH2O (structure I) and RE(H2O)7{kappa1N-B(CN)4}B(CN)42 (structure II) for RE = Y, Tb, Dy, Ho, Er, Tm, Yb, and Lu and n ≤ 3. Both structures have discrete eight-coordinate RE3+ complex cations, as RE(H2O)83+ in structure I and RE(H2O)7{kappa1N-B(CN)4}2+ in structure II. The heating of the compounds to temperature of ca. 160 °C gives anhydrous samples, but elongated heating to temperatures above ca. 200 °C leads to the slow decomposition of the tetracyanidoborates. The luminescence properties of a solid sample of the anhydrous Tb salt and a solution of the Dy salt were investigated. Both show intense lines in their excitation and emission spectra that were assigned to electronic transitions within the f and d shells.
New tetracyanidoborate salts with hydrated rare‐earth metal cations (RE3+) were obtained by the reaction of rare‐earth metal oxides or hydroxides with tetracyanidoboronic acid. A group of ...isostructural compounds was obtained, which has the chemical formula RE{B(CN)4}3(H2O)5·nH2O (RE = La, Ce, Pr, Nd, Sm, Eu, and Gd; n ≤ 0.5). In all compounds the rare‐earth metal cations have the coordination number nine with a RE‐O5N4 environment. They are connected to chains through one bridging tetracyanidoborate anion per RE3+ cation, according to RE{μ‐B(CN)4}{κN‐B(CN)4}2(H2O)5·nH2O. Solid samples of the Eu salt show luminescence with intense lines in the excitation and emission spectra caused by electronic transitions within the f and d shells.Thermal investigations indicate that all water molecules but one can be removed at temperatures below 160 °C and the last one by heating up to 340 °C. On further heating decomposition is observed.
Perylene bisimides (PBIs) are excellent dyes and versatile building blocks for supramolecular structures. Only recently have PBIs been shown to depict absorption characteristics of J-aggregates. We ...apply electronic structure calculations and femtosecond pump-probe spectroscopy to the monomeric, bay-substituted building-block of a PBI aggregate in dichloromethane to investigate its electronically excited states in order to provide the ingredients for the description of excitons in the aggregates and their annihilation processes. The PBI S(1)←S(0) absorption spectrum and the S(1)→S(0) emission spectrum have been assigned based on time-dependent Density Functional Theory calculations for the geometry-optimized electronic ground state and excited state structures in the gas phase. The monomeric absorption spectrum contains a strong transition at 580 nm and a broad shoulder between 575-500 nm, both features are attributed to a vibrational progression with an effective vibrational mode of 1415 cm(-1) whose major contributing vibrational normal modes are breathing modes of the perylene body. The effective vibrational mode of the emission spectrum is characterized by a frequency of 1369 cm(-1), whose major contributing vibrational normal modes are characterized by perylene and phenol (bay-substituent) CH bendings. The S(n)←S(1) excited state absorption spectrum is assigned based on Multi-Reference Configuration Interaction methodology. Here, we identify three transitions which give rise to two broad experimental features, one being located between 500 and 600 nm and the other one ranging from 650 to 750 nm.
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