The determination of zero-field splittings from measurements of spin-lattice relaxation times

We present an overview over eight brightly luminescent Cu(I) dimers of the type Cu2X2(P∩N)3 with X = Cl, Br, I and P∩N = 2-diphenylphosphino-pyridine (Ph2Ppy), 2-diphenylphosphino-pyrimidine (Ph2Ppym), 1-diphenylphosphino-isoquinoline (Ph2Piqn) including three new crystal structures (Cu2Br2(Ph2Ppy)3 1-Br, Cu2I2(Ph2Ppym)3 2-I and Cu2I2(Ph2Piqn)3 3-I). However, we mainly focus on their photo-luminescence properties. All compounds exhibit combined thermally activated delayed fluorescence (TADF) and phosphorescence at ambient temperature. Emission color, decay time and quantum yield vary over large ranges. For deeper characterization, we select Cu2I2(Ph2Ppy)3, 1-I, showing a quantum yield of 81%. DFT and SOC-TDDFT calculations provide insight into the electronic structures of the singlet S1 and triplet T1 states. Both stem from metal+iodide-to-ligand charge transfer transitions. Evaluation of the emission decay dynamics, measured from 1.2 ≤ T ≤ 300 K, gives ∆E(S1-T1) = 380 cm−1 (47 meV), a transition rate of k(S1→S0) = 2.25 × 106 s−1 (445 ns), T1 zero-field splittings, transition rates from the triplet substates and spin-lattice relaxation times. We also discuss the interplay of S1-TADF and T1-phosphorescence. The combined emission paths shorten the overall decay time. For OLED applications, utilization of both singlet and triplet harvesting can be highly favorable for improvement of the device performance.

Download Full-text

ChemInform Abstract: DETERMINATION OF THE CONFORMATION OF SUBSTITUTED 4,6-DIOXO-1,3-DIOXANES. PART III. CARBON-13 NMR CHEMICAL SHIFTS, 13C,H COUPLING CONSTANTS AND SPIN-LATTICE RELAXATION TIMES OF 2-, 2,2-, 2,5-, AND 2,2,5-SUBSTITUTED DERIVATIVES

Chemischer Informationsdienst ◽

10.1002/chin.197714044 ◽

1977 ◽

Vol 8 (14) ◽

pp. no-no

Author(s):

P. AEYRAES

Keyword(s):

Chemical Shifts ◽

Relaxation Times ◽

Lattice Relaxation ◽

Coupling Constants ◽

Spin Lattice Relaxation ◽

Nmr Chemical Shifts ◽

Spin Lattice

Download Full-text

Time Domain Zero Field NMR and NQR

Zeitschrift für Naturforschung A ◽

10.1515/zna-1986-1-286 ◽

1986 ◽

Vol 41 (1-2) ◽

pp. 440-444 ◽

Cited By ~ 1

Author(s):

A. Bielecki ◽

D. B. Zax ◽

A. M. Thayer ◽

J. M. Millar ◽

A. Pines

Keyword(s):

Time Domain ◽

Relaxation Times ◽

Low Frequency ◽

High Sensitivity ◽

Lattice Relaxation ◽

Spin Lattice Relaxation ◽

Zero Field ◽

Spin Lattice ◽

Field Cycling ◽

The Time Domain

Field cycling methods are described for the time domain measurement of nuclear quadrupolar and dipolar spectra in zero applied field. Since these techniques do not involve irradiation in zero field, they offer significant advantages in terms of resolution, sensitivity at low frequency, and the accessible range of spin lattice relaxation times. Sample data are shown which illustrate the high sensitivity and resolution attainable. Comparison is made to other field cycling methods, and an outline of basic instrumental requirements is given.

Download Full-text

A Selective Determination of the Proton Nuclear Relaxation Times of the Alkaloid Vindoline: An Extension via Fourier Transform Measurements

Canadian Journal of Chemistry ◽

10.1139/v74-130 ◽

1974 ◽

Vol 52 (5) ◽

pp. 829-832 ◽

Cited By ~ 6

Author(s):

L. D. Hall ◽

Caroline M. Preston

Keyword(s):

Fourier Transform ◽

Relaxation Times ◽

Lattice Relaxation ◽

Spin Lattice Relaxation ◽

Nuclear Relaxation ◽

Transform Method ◽

Fourier Transform Method ◽

Selective Determination ◽

Spin Lattice

A Fourier Transform method has been used to measure the spin–lattice relaxation times of essentially all the protons of the alkaloid, vindoline. It is shown that even for a molecule of this size substantial and potentially useful differences exist in the experimental relaxation times which reflect the degree of crowding of each proton by other protons.

Download Full-text