Reducing lifetime in Cu(i) complexes with thermally activated delayed fluorescence and phosphorescence promoted by chalcogenolate-diimine ligands

Article abstract of DOI:10.1039/d0tc03660a

Luminescent copper(i) complexes have drawn attention due to their promising performance as alternative optoelectronic materials to the well-known heavy transition metal complexes. Herein, we report the synthesis of six luminescent Cu(i) complexes with phosphines and 1,10-phenanthroline-derived ligands with thiadiazole and selenodiazole groups in order to evaluate the effect of the heavy atom on their photophysical properties. Steady-state and time-resolved spectroscopy confirmed delayed fluorescence emission via a thermally activated delayed fluorescence mechanism in all cases. The experimental spectroscopic data were analyzed with detailed quantum-chemical calculations. Interestingly, these complexes did not show the expected heavy atom effect that enhances the spin-orbit coupling matrix elements, but nevertheless the addition of the heavier chalcogens contributed to reducing the photoluminescence lifetime to roughly 800 ns, which is the lowest reported so far for such TADF materials. This journal is

Full text of DOI:10.1039/d0tc03660a

View Article Online
View Journal
Journal of
Materials Chemistry C
Materials for optical, magnetic and electronic devices
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: G. Farias, C. A.M.
Salla, R. da Silva Heying, A. J. Bortoluzzi, S. Curcio, T. Cazati, P. L. dos Santos, A. P. Monkman, B. D. Souza
and I. H. Bechtold, J. Mater. Chem. C, 2020, DOI: 10.1039/D0TC03660A.
Volume
Number
6
5
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
7
February 2018
Pages 911-1266
Journal of
Materials Chemistry C
Materials for optical, magnetic and electronic devices
rsc.li/materials-c
Accepted Manuscripts are published online shortly after acceptance,
before technical editing, formatting and proof reading. Using this free
service, authors can make their results available to the community, in
citable form, before we publish the edited article. We will replace this
Accepted Manuscript with the edited and formatted Advance Article as
soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes to the
text and/or graphics, which may alter content. The journal’s standard
Terms & Conditions and the Ethical guidelines still apply. In no event
shall the Royal Society of Chemistry be held responsible for any errors
or omissions in this Accepted Manuscript or any consequences arising
from the use of any information it contains.
ISSN 2050-7526
PAPER
Nosang V. Myung, Yong-Ho Choa et al.
A
noble gas sensor platform: linear dense assemblies of
a multi-layered
single-walled carbon nanotubes (LACNTs) in
ceramic/metal electrode system (MLES)
rsc.li/materials-c

Page 1 of 25
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/D0TC03660A
Reducing Lifetime in Cu(I) Complexes with Thermally Activated
Delayed Fluorescence and Phosphorescence promoted by
Chalcogenolate-Diimine Ligand
Giliandro Farias†, Cristian A.M. Salla#, Renata S. Heying†, Adailton J. Bortoluzi†, Sergio
F. Curcio$, Thiago Cazati$, Paloma L. dos Santos&, Andrew P. Monkman&, Bernardo de
Souza†*, Ivan H. Bechtold#*
*Corresponding authors: bernardo.souza@ufsc.br; tel: +55 48 37213608
ivan.bechtold@ufsc.br; tel: +55 48 37212304
†Department of Chemistry, Universidade Federal de Santa Catarina, 88040-900
Florianópolis, SC, Brazil
#Department of Physics, Universidade Federal de Santa Catarina, 88040-900
Florianópolis, SC, Brazil
$Department of Physics, Universidade Federal de Ouro Preto, 35400-000 Ouro Preto,
MG, Brazil
&Department of Physics, Durham University, South Road, Durham, DH1 3LE, U.K.
ABSTRACT
Luminescent copper(I) complexes have drawn attention due to their promising
performance as alternative optoelectronic materials to the well-known heavy transition
metals complexes. Herein, we report the synthesis of six luminescent Cu(I) complexes
with phosphines and 1,10-phenanthroline-derived ligands with thiadiazole and
selenodiazole groups in order to evaluate the effect of heavy atom on their photophysical
properties. Steady-state and time-resolved spectroscopy confirmed delayed fluorescence
emission via a thermally activated delayed fluorescence mechanism in all cases. The
experimental spectroscopic data was analyzed with detailed quantum-chemical
calculations. Interestingly, these complexes did not show the expected “heavy atom
effect”, that enhances the spin-orbit coupling matrix elements, but nevertheless the
addition of the heavier chalcogens contributed to reduce the photoluminescence lifetime
to roughly 800 ns, which is the lowest reported so far for such TADF materials.

Journal of Materials Chemistry C
Page 2 of 25
View Article Online
DOI: 10.1039/D0TC03660A
KEYWORDS: Copper(I) complexes, Heavy atom effect, TADF, phosphorescence.
INTRODUCTION
During the past three decades, many research groups have been studying
alternative luminescent materials to replace the most successful, currently employed
transition metal complexes, such as those of ruthenium, platinum, osmium, or iridium in
organic light emitting diodes (OLEDS).1–4 Cu(I) complexes gained attention due to their
promising optoelectronic performance, because of their low cost and high
photoluminescence quantum yields (PLQY), combined with easy color tuning by
variation of ligands.5–8 Indeed, copper appears to be particularly interesting due to its
spin-orbit coupling (SOC) constant of ξCu= 851 cm-1, which is known to facilitate ultrafast
intersystem crossing (ISC) Sn→Tn.9 Furthermore, mainly due to the pioneering work of
McMillin, it is known that Cu(I) complexes can exhibit thermally activated delayed
fluorescence (TADF).10–13
Heteroleptic complexes of the type [Cu(N^N)(P^P)]+, where N^N and P^P
indicate chelating diamine and diphosphine ligands respectively, presented promising
photophysical properties, e.g., highly luminescent Cu(I) complexes, with long-lived
excited-states. The low-lying Metal-to-Ligand Charge Transfer excited state (MLCT) of
these copper complexes determines their photophysical properties, and allows emission
in the visible region.6,14 As the LUMO of these complexes is usually centered on the
diamine, the HOMO-LUMO energy gap has been modulated employing different N-
heterocyclics, such as phenanthroline,15,16 bipyridyl-, pyrazolyl-,17triazolyl-,18 as well as
tetrazolyl-based ligands.19 By using these ligands, a variety of emission colors, including
blue and green, have already been reported.20–24
In contrast to the heavier metal elements, the SOC in copper is much weaker, and
the ligands are not generally able to enhance the SOC in these complexes. Consequently,
cuprous phosphorescent complexes usually possess long emission lifetimes of up to a
hundred of microseconds. Unfortunately, the long decay times of triplet states facilitate
triplet–triplet annihilation (TTA) and triplet-polaron quenching (TPA) in
electroluminescence devices25 limiting their efficiency. However, this detrimental effect
can be avoided by the fact that many emissive cuprous complexes can also emit efficiently
through TADF mechanism at room temperature, when there is a small energy gap
between singlet (S1) and triplet (T1) states.26–29 Designing these compounds with short

Page 3 of 25
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/D0TC03660A
combined TADF and phosphorescence decay times and high PLQYs is still a challenge.
For instance, radiative decay times of [Cu(N^N)(P^P)]+ complexes of less than 2–5 μs
have not been reported so far.6,28,30
Recently, we reported two 1,10-phenanthroline-derived ligands with the
thiadiazole and selenodiazole groups, where the heavy atom effect was observed in the
photophysics of the ligands and ruthenium complexes. The ligand with a selenodiazole
group showed an increase of 200 times in the spin-orbit coupling matrix elements and
even phosphorescence emission,31 and the ruthenium(II) complexes also had their
properties altered.32 These results pointed to a promising effect of the heavy atoms in
luminescent complexes and a possibility to enhance the SOC in cuprous complexes.
Here we report the synthesis and characterization of six luminescent Cu(I)
complexes with phosphines and 1,10-phenanthroline-derived ligands with the thiadiazole
and selenodiazole groups, [1,2,5]thiadiazolo[3,4-f][1,10]phenanthroline (TDZP) and
[1,2,5]selenadiazolo[3,4-f][1,10]phenanthroline (PhenSe) (Chart 1). The complexes have
been fully characterized using steady-state and time-resolved spectroscopy, and for all
them, crystals have been obtained allowing a full crystallographic analysis. The
experimental spectroscopic data have been further rationalized by means of detailed
quantum-chemical calculations.
Chart 1. Cu(I) complexes discussed in the introductory part.

Journal of Materials Chemistry C
Page 4 of 25
View Article Online
DOI: 10.1039/D0TC03660A
RESULTS AND DISCUSSION
Synthesis and Characterization
The copper complexes were prepared in excellent yield by a quick reaction of
[Cu(CH3CN)4]BF4 with the phosphines and diimines ligands in CH2Cl2. All final
complexes were obtained from crystallization in THF/dichloromethane and used without
further purifications. A synthetic route for these is shown in Scheme S1. The obtained
compounds are stable in air at least for several months without oxidizing.
The molecular structure of the complexes was determined by single crystal X-ray
diffraction studies. The Cu(I) center in the four new complexes (S1, Se1, S2 and Se2) has
a distorted tetrahedral geometry, observed by the strong deviation from the tetrahedral
angle around the Cu(I) center, where the dihedral angle between N-Cu-N and P-Cu-P
planes are measured to be 76.6 ° for S1, 73.0 ° for Se1, 78.3 ° for S2 and 70.5 ° for Se2.
This situation reflects the specific steric requirements of the ligands, and the stabilization
by intramolecular π-stacking interactions, found in many other transition complexes with
phosphine ligands.15 Also, for S2 and Se2, most Cu-P and Cu-N distances are closer than
those with PPh3 ligand. The oxygen atom of the POP ligand in the complexes is at a
distance of  3 Å away from the Cu(I) center, and opposite to the coordinated N atoms,
indicating a weak interaction between the oxygen atom and Cu(I) center. This suggests
that the POP ligand is in closer proximity to the copper atom due to the ether linkage,
which is known to increase the probability of charger transfer from the metal to ligand
(see below). Bond distances and angles are reported at Table 1 and are similar to those of
C1 and C2 previously reported.15
Table 1. Selected bond lengths [Å] for C1-Se2.
C1a
2.080
2.070
2.271
2.245
-
S1
Se1
C2a
S2
Se2
Cu-N1
Cu-N10
2.0877(14)
2.0827(14)
2.2588(4)
2.2662(5)
-
2.087(2)
2.088(2)
2.2637(7)
2.2731(8)
-
2.071
2.063
2.261
2.231
3.205
80.83
110.81
108.12
109.08
2.0716(13)
2.0586(12)
2.2546(4)
2.2238(4)
3.0391(10)
80.75(5)
2.070(3)
2.040(2)
2.2567(8)
2.2197(8)
3.105(2)
81.11(10)
107.31(7)
117.47(3)
110.73(7)
Cu-P1
Cu-P2
Cu···O
N1-Cu-N10
P1-Cu-N1
P2-Cu-P1
N10-Cu-P2
80.90
115.44
118.69
103.60
80.01(5)
117.88(4)
116.151(17)
112.67(4)
79.93(8)
111.09(6)
115.75(3)
113.68(6)
105.87(4)
112.573(15)
119.99(4)

Page 5 of 25
Journal of Materials Chemistry C
a 15
View Article Online
DOI: 10.1039/D0TC03660A
.
S1
Se1
S2
Se2
Fig. 1. ORTEP plot (thermal ellipsoid with 50% probability) of the molecular structure
of cation complexes S1, Se1, S2 and Se2. Hydrogens atoms and most of atoms labels are
omitted for clarity.
Thermogravimetric analysis (TGA) of C1–Se2 under nitrogen atmosphere
revealed that the initial decomposition temperatures were close to 130 °C for C1, S1, Se1
and C2 and 350 °C for S2 and Se2 (See Fig. S7). Such thermal stability indicates that all
the complexes can undergo thermal treatments until at least 100 °C in device fabrication.

Journal of Materials Chemistry C
Page 6 of 25
View Article Online
DOI: 10.1039/D0TC03660A
Cyclic voltammetry in CH2Cl2 solution was performed to estimate the HOMO and
LUMO levels from the oxidation and reduction potentials, respectively. Fig. 2 shows the
cyclic voltammograms and Table 2 summarizes the electrochemical data. All complexes
displayed one anodic process, which is attributed to the oxidation of the copper center.
This process is usually quite positive and irreversible due to the dissociation of the
complex in solution. The phosphine group had a small effect on the oxidation potential,
with the complexes bound to triphenylphosphine having a higher potential when
compared with the analogous with the POP ligand, in agreement with the obtained Cu-P
distances. In addition, a cathodic process was observed for the complexes S1, Se1, S2 e
Se2. The reversible process of reduction was attributed to redox processes of the ligands
TDZP e PhenSe, also observed for the free ligands.31 The HOMO and LUMO energies
obtained from voltammetry agree with the calculated trend from DFT, where the
contribution from both the copper atom and the ligands on these frontier orbitals was
predicted.
15
C1
S1
Se1
C2
S2
10
5
Se2
0
-5
-2,0
-1,5
-1,0
-0,5
0,0
0,5
1,0
Potential vs Fc/Fc+ / V
Fig. 2. Cyclic voltammograms of C1-Se2 in 1×10-3 mol L-1 CH2Cl2 solutions under
nitrogen atmosphere. The scanning rate is 100 mV s-1. Three electrodes electrochemical
cell: Gold (working); Pt wire (auxiliary); and Ag/Ag+ (reference). Supporting electrolyte:
0.1 mol L-1 n-Bu4NBF4.

Page 7 of 25
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/D0TC03660A
Table 2. Electrochemical properties of C1-Se2.
Electrochemical
Optical
Bandgapc / eV
2.93
Complex
Ereda/ V
Eoxa / V
EHOMOb/ V
ELUMOb/ V
Bandgap / eV
C1
S1
-
0.79
0.88
0.86
0.75
0.83
0.81
-5.59
-5.68
-5.66
-5.55
-5.63
-5.61
-2.66d
-2.97
-3.01
-2.81d
-2.99
-3.09
-
-1.83
-1.79
-
2.71
2.65
-
2.75
Se1
C2
S2
2.68
2.74
-1.81
-1.71
2.64
2.52
2.69
Se2
2.62
a Determined from peak potentials. b Calculated from EHOMO = –(4.8 + Eox) and ELUMO
=
–(4.8 – Ered).c Calculated from the onset of the absorption spectra in solution. d Obtained
from the sum of the LUMO energy and optical band gap.
Photophysical Properties
The UV-Vis absorption and emission of complexes C1-Se2 were performed in
CH2Cl2 solution (see Fig. 2 and S9), and with the complexes dispersed 10 wt% in a
PMMA matrix (Fig. 2 and S8). All photophysical data are summarized in Table 3. The
complexes exhibited an intense absorption band around 250 nm, which is attributed to a
π→π* transition of the phosphine ligand. The less intense absorption bands with maxima
between 300 and 350 nm, are related to the diamine ligand,31 and could be mainly
attributed to intra-ligand charge transfer transitions. As the lower energy absorption band
around 400 nm is not present in the ligands, it is safely assigned to spin allowed MLCT
involving 3d orbitals of Cu(I) and π* orbitals of diamine.6,15 Moreover, the molar
absorptivity for the MLCT follows the order PhenSe > TDZP > phen (in exception of S1)
and POP > PPh3. However it is not related to the allowedness of the S0 → S1 transition,
but to the existence of new MLCT states involving the thiadiazole and selenodiazole
moieties with close energy, as verified by TD-DFT. The absorption in PMMA was found
to be very similar to solution.

Journal of Materials Chemistry C
Page 8 of 25
View Article Online
DOI: 10.1039/D0TC03660A
Table 3. Photophysical data for the Cu(I) complexes in CH2Cl2 solution and 10 wt%
PMMA films.
Solutiona
PMMA films
λabs(nm) /
Stokes
shift
e
τ
krd ×
knr ×
ε (L mol-1 λem(nm)
λabs(nm) λem(nm)
Φb
(µs)c 105 s-1 105 s-1
cm-1)
(nm)
352 / 2772
370 / 1808
375 / 3232
391 / 2840
404 / 3881
396 / 4252
606
610
615
628
624
637
350
370
380
390
395
400
550
577
592
560
594
605
10390
0.11
0.04
0.08
0.13
0.06
0.08
2.7
1.1
1.1
2.1
1.2
0.8
0.41
0.36
0.73
0.62
0.50
1.00
3.30
8.73
8.36
4.14
7.83
11.50
C1
S1
Se1
C2
S2
170
199
205
Se2
a In CH2Cl2 at 1.010-5 mol L-1. b The uncertainty in Φ was ±0.01. c The uncertainty of the
lifetime was estimated in ± 0.1 µs. dkr = Φ / τ. eknr = (1 - Φ) / τ.
The emission from a degassed solution under excitation of the MLCT band is in
the orange region, with maxima at 606, 610, 615, 628, 624 and 637 nm, for C1-Se2,
respectively. The emission peaks observed using the PMMA matrix were located in the
yellow-orange region, with maxima at 550, 577, 592, 560, 594 and 605 nm for C1-Se2,
respectively. These spectra have broad and unstructured gaussian lineshapes, which is in
accordance with the MLCT nature of the emitting state. Moreover, the luminescence
properties strongly depend on the environment. For instance, as depicted in Fig. 3 and
Fig. S9, C1 shows emission in λmax = 604 nm in solution and λmax = 550 nm in PMMA.
Similar trends are observed for the other complexes. These observations can be explained
considering the changes in the molecular geometry of the Cu(I) compounds, which take
place after MLCT excitation. In the electronic ground state (d10 configuration), the
complexes have a pseudo-tetrahedral coordination of the metal ion, whereas in the MLCT
excited state, with a d9 configuration of the metal ion, a flattening distortion of the
molecular structure occurs.7 Therefore, in a rigid matrix these distortions are less
favorable, and a higher energy emission is observed. Furthermore, as the emission results
from a CT state, it is also influenced by the polarity of the solvent. Thus, as CH2Cl2 has
a larger polarity than PMMA, a lower energy emission in CH2Cl2 was expected.

Page 9 of 25
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/D0TC03660A
6x104
5x104
4x104
3x104
2x104
C1
S1
Se1
C2
S2
1.0
0.8
0.6
0.4
0.2
0.0
Se2
1x104
0
300
400
500
600
700
Wavelength /nm
Fig. 3. Optical absorption spectra of the Cu(I) complexes in CH2Cl2 solution 1.0ꢀ×ꢀ10–
5ꢀmolꢀL–1 and emission spectra of the studied Cu(I) complexes 10 wt% in PMMA.
Emission spectra were obtained with excitation at the lowest energy band absorption
maximum.
The PLQY (Φ) and the excited-state lifetimes (τ) for the complexes embedded in
the PMMA matrix are shown in Table 3. Interestingly, the presence of the heavy atom
reduced both PLQY and lifetime of S1, Se1, S2, and Se2, compared to their reference
compounds C1 and C2. For complexes with TDZP and PhenSe, the lifetimes were
measured in the range of 2.7 µs to 800 ns (Table S3 and Fig. S11). Based on these results,
the radiative and nonradiative constants, kr and knr, were calculated (Table 3). The kr
follow the order Se1> C1>S1 and Se2> C2>S2, indicating that the presence of the PhenSe
with a heavy atom enhances the radiative path, while TDZP do not. On the other hand,
for all these new complexes the nonradiative path is enhanced too. Such an increase of
the nonradiative rate is more pronounced in complexes with TDZP and PhenSe, and is
attributed to the lower triplet energy (see below) and the intramolecular π-stacking
interactions (comparing the dihedral angle). The presence of the thiadiazole and
selenodiazole moieties, distort the complexes from their tetrahedral geometry, as
mentioned before, increasing the know pseudo-Jahn-Teller effect in the excited state.33

Journal of Materials Chemistry C
Page 10 of 25
View Article Online
DOI: 10.1039/D0TC03660A
a)
C1
S1
Se1
C2
S2
100
10-2
10-4
10-6
10-8
Se2
PF
TADF + Phosp
10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100
Time Delay / s
b)
C1
S1
Se1
C2
S2
100
10-2
10-4
10-6
10-8
10-10
Se2
PF
TADF + Phosp
10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100
Time Delay / s
c)
100
10-2
10-4
10-6
10-8
10-10
Temperature
80 K
130 K
180 K
230 K
280 K
320 K
Temperature
10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 100
Time Delay / s
Fig. 4. Time resolved normalized emission spectra at room temperature for C1-Se2 10
wt% in PMMA, at 300K (a), 80K (b) and temperature dependence for compound C1 from
80 K to 320 K, with a 50 K step (c).
Time-resolved spectroscopy was used to follow the excited state dynamics of
complexes C1-Se2. At room temperature, the luminescence is characterized by a fast

Page 11 of 25
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/D0TC03660A
component followed by a slow bi-exponential decay. The decays obtained as a function
of temperature for all complexes exhibit clear temperature dependence in the delayed
fluorescence region (microsecond range), which is characteristic of a TADF mechanism.
Fig. 4 shows the emission decays at room temperature (a) and at 80K (b) for all
compounds. In Fig. 4c, a more detailed temperature dependence is shown for compound
C1 from 80 K to 320 K, with a 50 K step. In all compounds, the delayed fluorescence
emission (microsecond range) shows higher intensity at higher temperatures, which is a
characteristic of the TADF mechanism. On the other hand, the longer-lived emission
(millisecond range) shows the opposite behavior, the intensity increases by cooling down
the films, which is also consistent with a slower depopulation of the triplet state via rISC,
thus increasing the phosphorescence intensity.
The time resolved emission spectra collected at room temperature and at 80K are
shown in Fig. 5 for C1 and S11-15 at the supporting information for C2-Se2. In the early-
collected time resolved emission spectra (1-40 ns), a fast emission at high energy was
observed, which is attributed to the prompt fluorescence component as suggested by Li
and co-workers.36 Afterwards, in the microsecond range a new emission is observed close
to 550 nm, which is attributed to the triplet state of these compounds. Subsequently, a
blue shift is observed in the microsecond range due to the thermal repopulation of the
singlet state and consequent mixing of emitting species, i.e. delayed fluorescence and
phosphorescence emission. The time resolved emission spectra collected at different
temperatures shows a larger blue-shift at lower temperature. These observations are
consistent with the presence of thermalized triplet states at higher temperatures.

Journal of Materials Chemistry C
Page 12 of 25
View Article Online
DOI: 10.1039/D0TC03660A
Time Delay / ns:
Time Delay / s:
C1
RT
C1
RT
1,2
1,0
0,8
0,6
0,4
0,2
0,0
1,2
1,0
0,8
0,6
0,4
0,2
0,0
1.1
14.1
Time Delay
Time Delay
3.3
19.9
5.7
28.2
8.4
39.8
11.5
14.9
18.8
23.1
39.6
56.2
79.4
112.2
158.5
223.9
316.2
400
500
600
700
500
600
700
Wavelength / nm
Wavelength / nm
Time Delay / s:
Time Delay / ns:
C1
80 K
C1
80 K
1,2
1,0
0,8
0,6
0,4
0,2
0,0
1,2
1,0
0,8
0,6
0,4
0,2
0,0
31.6
1.1
Time Delay
Time Delay
5.7
3981.1
11.5
18.8
23.1
33.5
500
600
700
400
500
600
700
Wavelength / nm
Wavelength / nm
Fig. 5. Time resolved normalized emission spectra at room temperature (up) and 80K
(down) for C1 10 wt% in PMMA. Films were excited at 355 nm.
The S1 and T1 energies (Table 4) were obtained from the onset of the highest and
the lowest energy emission from the time-resolved emission spectra at room temperature
and 80 K (µs time frame), respectively. As can be observed, the S1 energy decreases in
the presence of the TDZP and PhenSe ligands and also for POP complexes, in agreement
with the bathochromic shift observed in the absorption spectra and the steady state
emission. The T1 energy follows the same trend, being lower for S1 and Se2. As the knr
increases when the energy difference between T1 and the ground state decreases,35 the
higher knr for complexes with TDZP and PhenSe ligands can be attributed to structural
distortions, as mentioned before, and the lower triplet state energy for these complexes.
In addition, the ΔE(S1-T1) which is determinant to a faster TADF component into the
emission, decreases for complexes with TDZP and PhenSe and POP ligands. Therefore,
the lower lifetime obtained for Se1 and Se2 can be partially attributed to the fast
reconversion from T1 to S1, which corresponds to a faster TADF. However, such a low
lifetime for Cu(I) complexes is only possible considering a component of
phosphorescence into the emission. Thus, as the phosphorescence decay path depends on

Page 13 of 25
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/D0TC03660A
both triplet energy and the SOC between the singlet and triplet states, one can expect a
lower phosphorescence component for complexes with TDZP and PhenSe moieties.
Table 4. Singlet and Triplet energies obtained from time-resolved spectroscopy.
C1
S1
Se1
2.68
2.51
0.17
C2
S2
Se2
2.54
2.42
0.12
S1/ eV
T1 / eV
2.77
2.53
0.24
2.67
2.46
0.21
2.73
2.52
0.21
2.57
2.43
0.14
ΔES1-T1 / eV
Density Functional Theory/Time-Dependent DFT Approaches and Photophysical
Interpretations
In order to achieve further insights into the nature of the excited states and the
emission mechanism, the optimized geometries for the ground state of all complexes were
obtained using DFT at the PBE0/def2-TVZP(-f) level. The S0 geometries are shown in
Fig. S16 and the important lengths and angles are listed in Table S4. The vibrational
frequencies confirm that the geometries correspond to a minimum of the surface energy
potential, since no negative frequencies were found. Moreover, the predicted S0 geometry
for all complexes are in good agreement with the experiment, where the maximum
average error found for bond lengths was of 2.4%, and of 6.6% for bond angles, which
supports further use of PBE0 in subsequent investigations.
The first insight into the electronic properties of these complexes can be obtained
from the calculated HOMO and LUMO, see Fig. 6. For these complexes the HOMO
(isosurface with transparency) is largely derived from a 3d atomic orbital of the copper
(I) center with significant contributions from the coordinating phosphorous atoms,
whereas the LUMO is mainly distributed over the diamine. However, the LUMO for C1
and C2 is mostly distributed over phenanthroline moiety, while for the complexes with
TDZP and PhenSe the LUMO is centered at the thiazole and selenodiazole, respectively.
Thus, the lower energy excited states are expected to be MLCT-like, but involving
different π* orbitals of diamine. Indeed, TD-DFT calculations showed that the low-lying
S1 and T1 states are more than 88% HOMO→LUMO transitions in S1 and mixed
HOMO→LUMO and HOMO→LUMO-1 (both MLCT) for T1 (Table S5-S7), being
assigned as 1MLCT and 3MLCT, respectively.

Journal of Materials Chemistry C
Page 14 of 25
View Article Online
DOI: 10.1039/D0TC03660A
C1
S1
Se1
C2
S2
Se2
Fig. 6. Frontier molecular orbitals of complexes C1–Se2 calculated using PBE0/def2‐
TZVP(‐f). The HOMO is shown as the isosurface with transparency.
The LUMO orbital centered at thiazole and selenodiazole moieties also minimize
the HOMO and LUMO overlap (Fig. S17) by increasing the spatial separation of these
orbitals. That results in a smaller ΔES1-T1, as also obtained from the spectroscopic studies,
and agrees well with the calculated ΔES1-T1 using the adiabatic energy for such states
(Table 5). This larger spatial separation of HOMO and LUMO also reduce the oscillator
strength f of the S0 → S1 transition (1MLCT) for complexes with TDZP and PhenSe
ligands. Even so, the presence of these ligands resulted in new low energy MLCT states,
d→π*(thiadiazole or selenodiazole), close to the d→π*(phen). The net result is a wider
and more intense absorption band, as observed in the experimental spectra (compare
Table S5-S7 and Fig. S18).
Table 5. Data of SOC-TD-DFT and adiabatic energy difference for C1-Se2.
C1
S1
Se1
6.09
C2
S2
26.07
2.76
Se2
4.44
0.96
9.70
99.99
⟨T1|ĤSO|S0⟩a
⟨T1|ĤSO|S1⟩a
⟨T1|ĤSO|S2⟩a
⟨T1|ĤSO|S3⟩a
22.50
17.11
6.37
24.55
8.12
37.79
27.65
6.32
2.01
24.42
156.94
9.07
2.59
157.98
112.72
119.62
152.47

Page 15 of 25
Journal of Materials Chemistry C
⟨T1|ĤSO|S4⟩a
⟨T1|ĤSO|S5⟩a
166.35
4.70
17.36
130.82
66.77
128.53
189.82
211.05 D1O1I: 610..71023V9ie/Dw0ATrtCic0le3O6n6l0inAe
180.85
9.82
99.53
8.36
15.72
10.24
22.37
34.46
111.44
5.43
2.46
42.32
3.83
12.33
21.16
13.55
34.32
87.76
29.88
26.17
26.17
4.25
31.84
4.08
⟨T2|ĤSO|S0⟩
⟨T2|ĤSO|S1⟩a
⟨T2|ĤSO|S2⟩a
⟨T2|ĤSO|S3⟩a
⟨T2|ĤSO|S4⟩a
⟨T2|ĤSO|S5⟩a
12.97
2.51
18.27
71.51
59.59
88.94
12.82
118.22
90.82
123.04
14.77
23.44
12.95
6.79
36.34
Σ ⟨T |ĤSO|S푖⟩
577.59
478.73
611.95
707.73
512.50
712.14
푗
b
S1 / eV
2.79
2.42
0.37
0.24
2.35
2.09
0.26
0.21
2.16
1.98
0.18
0.17
2.79
2.42
0.37
0.21
2.46
2.32
0.14
0.14
2.29
2.23
0.06
0.12
b
T1 / eV
ΔES1-T1 Theo / eV
ΔES1-T1 Exp / eV
a √ Σ Tj (MS=0,±1)|ĤSO|Si2 at the S0 optimized geometry; b Adiabatic energy.
For many Cu(I) complexes, SOC effects provide distinct phosphorescence decay
paths in addition to the TADF via S1. Therefore, to evaluate both the phosphorescence
and the TADF decay paths for C1-Se2 in terms of SOC, we calculate the SOC matrix
elements between the first 10 singlet and triplet states,36 on top of S0 geometries. The
SOC matrix elements, between the first six singlets and the first two triplet states which
should have the appreciable contribution to the phosphorescence and the TADF
mechanism in these complexes, are shown in Table 5. As one can see, the SOC between
S1 and T1, both mainly involving the MLCT transition with same d orbital, decreases for
complexes with TDZP and PhenSe and shows that the d→π*(thiadiazole or
selenodiazole) transition does not result in a significant heavy atom effect in the SOC,
even for Se1 and Se2, where the selenium atom is present. As the SOC between these
states is mostly associated with MLCT transitions, having components of both the copper
and the phenanthroline ligand, the presence of the copper atom ultimately determines the
magnitude of the SOC matrix element.37 Also, as the SOC matrix elements have a
distance dependence, it was observed that the ligands with thiadiazole and selenodiazole
moieties have a LUMO that is too far from the copper atom, and their contribution to the
SOC matrix elements decrease. On other hand, the SOC between states with d→π*(phen)
configuration is close for all complexes and when high energy singlet states, i.e. S3 or S4,
are involved, as these states result from MLCT transitions involving different d orbitals

Journal of Materials Chemistry C
Page 16 of 25
View Article Online
from that of T1 or T2 (see Fig. S19 and Table S5-S7) a high SOC matrix eDleOmI: 1e0.n10t39i/sD0TC03660A
observed.
By adding the SOC matrix elements, one can more accurately reflect about the
phosphoresce and TADF decay paths, as both, kphosp and kTADF depend on that. In Table
5, the sum of SOC matrix elements of these complexes follows the order Se1> C1>S1
and Se2>C2>S2, which is the same order of the radiative constant obtained
experimentally. However, the kphosp has a dependence on the triplet energy, while the
kTADF relies on an exponential of the ΔE(S1-T1). Thus, as the triplet energy decreases from
C1 to Se1 and from C2 to Se2, the phosphorescence rate should be higher for
phenanthroline complexes, and the lower contribution of the phosphorescence into the
emission should be found for TDZP complexes, due to the combined low triplet energy
and SOC matrix elements. On the other hand, for the TADF path, as the ΔE(S1-T1) also
decreases from C1 to Se1 and from C2 to Se2, this emission component should follow
the same order.
We can conclude that, even structurally similar, the presence of TDZP and PhenSe
ligands significantly change the photophysical properties, as shown in Scheme 1 for
complexes C2-Se2. For these complexes, the introduction of thiadiazole and
selenodiazole moieties resulted in a low-lying 1,3MLCT state involving them. Thus, the
lowest ΔES1-T1 values were found for those complexes with chalcogenide atoms, due to
the minimization of the HOMO and LUMO overlap through increasing the spatial
separation of the HOMO and LUMO, reducing the electron exchange by changing the
ligand. Therefore, the krISC, which is determinant to the TADF mechanism and has an
exponential dependence with the energy gap between these states, favors the reverse ISC
for complexes Se1 and Se2. In addition, the introduction of TDZP and PhenSe provides
a slower phosphorescence decay path. Besides, the combined TADF and
phosphorescence paths significantly decrease the overall lifetime, which can be explored
further in more efficient materials.

Page 17 of 25
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/D0TC03660A
Scheme 1. Energy levels diagram for compounds C2-Se2. Vertical states and their major
configuration obtained using the SOC-TD-DFT approach on top of S0 optimized
geometry. The calculated ΔES1-T1 is the adiabatic energy difference for these states. The
symbols “>” and “>>” compare the contribution of the same constant between the
different compounds using C2 as reference.
CONCLUSION
The synthesis and characterization of a new series of copper(I) complexes with
phenanthroline ligands was presented. The complexes showed thermally activated
delayed fluorescence emission determined by steady-state and time-resolved
spectroscopy. The experimental spectroscopic data were further rationalized by means of
detailed quantum-chemical calculations. The molecules studied here did not show the
classical heavy-atom effect in terms of the spin-orbit coupling matrix elements, where
reduction in the ΔES1-T1 energy gap, which is determinant for the TADF mechanism by
favoring the reverse ISC, combined to the phosphorescence decay, decreased the lifetime
of the complexes. This is achieved through increasing the spatial separation of HOMO
and LUMO. For Se2, the lifetime was as low as 800 ns, the lowest reported so far for
[Cu(N^N)(P^P)]+ complexes. These results point to new a way of reducing the lifetime
in copper(I) complexes, minimizing the HOMO and LUMO overlap by increasing their
spatial distance.

Journal of Materials Chemistry C
Page 18 of 25
View Article Online
DOI: 10.1039/D0TC03660A
EXPERIMENTAL SECTION
General Procedures
All starting materials were purchased from Aldrich, Acros, Merck or Vetec and
were used without further purification.
The measurements of carbon, hydrogen and nitrogen percentages of the ligands
and the synthesized complexes were performed on a C, H, N - Perkin-Elmer 2400
elemental analyzer. The spectra in the infrared region were obtained in a Perkin Elmer
Spectrum 100 spectrophotometer, in the region of 4000 to 450 cm-1. The method of
attenuated total reflectance (ATR) was used to analyze all samples.
The X-ray diffraction analysis was performed on a Bruker APEX II DUO
diffractometer using radiation generated by a molybdenum tube (MoKαλ = 0.71073 Ǻ)
and graphite monochromator. During analyses the sample were sustained at 200K. The
crystal structures was solved by direct methods and refined by the least squares method
with complete matrix, using the programs Bruker APEX II software package38 and
SHELXL-2018 respectively.39 The graphical representations of the molecular structures
were generated using the program PLATON.40 Squeeze procedure was applied to S1 and
Se1 complexes using PLATON Crystallographic Tools.40 Disordered counterion and
solvate were modeled for Se2 complex. Full crystallographic tables (including structure
factors) for both complexes have been deposited with the Cambridge Crystallographic
Data Centre as supplementary publication numbers CCDC-2006226-2006229. These data
can be obtained free of charge from the Cambridge Crystallographic Data Centre at
www.ccdc.cam.ac.uk.
Emission decay were obtained through the time-correlated single photon counting
technique, using aFluoTime200 (PicoQuant) spectrometer. The excitation was performed
by a 401 nm pulsed diode laser with repetition rate ranging from 0.25 to 20.0 MHz.
Emission was collected perpendicular to excitation and passed through a polarizer set at
the magic angle. The detection system consisted of a monochromator and a microchannel
plate photomultiplier (Hamamatsu R3809U-50). Lifetimes were obtained by fitting the
emission decays to a convolution of the instrument response function and the sum of
exponentials using the FluoFit® software. The plots of weighted residuals and reduced

Page 19 of 25
Journal of Materials Chemistry C
2
View Article Online
DOI: 10.1039/D0TC03660A
chi-squared ( ) were used to accurately determine the quality of the fittings during the
analysis procedure.
Synthesis and Characterization
[Cu(Phen)(PPh3)2]BF4 (C1). Under argon, PPh3 (105 mg, 0.4 mmol) was dissolved in dry
dichloremethane (20 mL). Tetrakis(acetonitrile)copper(I) tetrafluoroborate (63 mg, 0.2
mmol) was added to this solution, and the reaction mixture was refluxed for 30 min, then
Phen (40 mg, 0.2 mmol) was added. The mixture was refluxed for another half hour. The
solvent was removed by evaporation. The crude product was further purified by
recrystallization from the mixed solvent of tetrahydrofuran/dichloromethane (80:20).
Yield: 61 %; IR (KBr), in cm-1: ν (C-Har) 3057 – 2862, ν (C=N e C=C) 1670 – 1432, ν
(B-F) 1055, δ (C-Har) 843 – 510; C48H38BCuF4N2P2 (855.13): calcd. C 67.13, H 4.80, N
3.28; found C 67.42, H 4.48, N 3.28.
[Cu(TDZP)(PPh3)2]BF4 (S1). S1 was synthesized by the same method that of C1, except
that Phen was replaced by TDZP (48 mg, 0.2 mmol). Yield: 90 %; IR (KBr), in cm-1: ν
(C-Har) 3057, ν (C=N e C=C) 1585 – 1399, ν (B-F) 1053, δ (C-Har) 817 – 515;
C46H42BCuF4N4P2S+1.5 THF (1021.35): calcd. C 63.35, H 4.51, N 5.12; found C 63.50,
H 4.74, N 5.49.
[Cu(PhenSe)(PPh3)2]BF4 (Se1). Se1 was synthesized by the same method that of C1,
except that Phen was replaced by PhenSe (57 mg, 0.2 mmol). Yield: 87 %; IR (KBr), in
cm-1: ν (C-Har) 3050 – 2849, ν(C=N e C=C) 1599 – 1399, ν (B-F) 1059, δ (C-Har) 816 –
512; C48H44BCuF4N4P2Se+2 THF: calcd. C 60.51, H 4.66, N 4.75; found C 60.91, H
4.75, N 5.07.
[Cu(Phen)(POP)]BF4 (C2). C2 was synthesized by the same method that of C1, except
that PPh3 was replaced by POP (107 mg, 0.2 mmol). Yield: 90 %; IR (KBr), in cm-1: ν
(C-Har) 3058 – 2954, ν (C=N e C=C) 1768 – 1435, ν (C-O) 1207, ʋ (B-F) 1054, δ (C-
Har) 846 - 513. C48H40BCuF4N2OP2+1 THF: calcd. C 64.52, H 4.77, N 2.95; found C
64.76, H 4.64, N 2,89.
[Cu(TDZP)(POP)]BF4 (S2). S2 was synthesized by the same method that of C2, except
that Phen was replaced by TDZP (48 mg, 0.2 mmol). Yield: 93 %; IR (KBr), in cm-1: v

Journal of Materials Chemistry C
Page 20 of 25
View Article Online
DOI: 10.1039/D0TC03660A
(C-Har) 3050, ν (C=N e C=C) 1566 – 1405; ν (C-O) 1212; ν (B-F) 1053; δ (C-Har) 816
- 497. C56H50BCuF4N4O3P2S: calcd. C 62.84; H 4.58; N 5.18; found C 62.78; H 4.70; N
5.23.
[Cu(PhenSe)(POP)]BF4 (Se2). Se2 was synthesized by the same method that of C2,
except that Phen was replaced by PhenSe (57 mg, 0.2 mmol). Yield: 94 %; IR (KBr), in
cm-1: ν (C-Har) 3064 – 2856, ν (C=N e C=C) 1566 – 1434; ν (C-O) 1212; ν (B-F) 1059;
δ (C-Har) 872 - 512. C56H50BCuF4N4O3P2Se: calcd. C 60.34, H 4.23, N 4.87; found: C
60.15, H 4.51, N 5.01.
Thermogravimetric Analyses and Cyclic Voltammetry Studies
The thermogravimetric analysis was performed with approximately 2 mg of
sample in a platinum crucible, with a nitrogen flow of 100 mL min-1 and a heating ramp
of 10 °C min-1 in a temperature range of 30-900 °C. The equipment used is of the brand
Shimadzu, model TGA-50.
The redox behavior of the complexes was investigated by square wave
voltammetry in a potentiostat-galvanostat BAS (Bioanalytical Systems, Inc.) model
Epsilon. A concentration of 2.510-4 mol L-1 in CH2Cl2 solution was used under nitrogen
atmosphere. Tetrabutylammonium hexafluorophosphate (0.1 mol L-1) was used as
support electrolyte and the electrochemical cell was composed of three electrodes: work
- vitreous carbon; auxiliary - platinum wire; reference - Ag/Ag+. For correction of the
reference electrode the ferrocene (E1/2 vs NHE = 398 mV) was used.
Spectroscopic Measurements
The electronic spectra in the ultraviolet, visible and near infrared regions were
obtained for all the complexes in the range of 200−800 nm in a Perkin-Elmer
spectrophotometer model Lambda-750. The values of ε are given in L mol-1 cm-1. The
emission spectra were obtained on a Varian Cary Eclipse Fluorescence
spectrophotometer. The spectroscopy measurements were performed in CH2Cl2 solution
and solid state using PMMA matrix containing 10 wt% ofC1-Se2. The analyzes were
performed using spectroscopic grade solvents, substrates and quartz cuvettes with a
capacity of 1 mL and 1.00 cm of optical path at 25 ºC. Absolute quantum yields (Φ) were

Page 21 of 25
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/D0TC03660A
made using a Hamamatsu Photonics Absolute Quantum Yield Measurement System
model c9920-02G which is based on the integrating sphere method.
Singlet-excited state photoluminescence decay curves were recorded using the
time-correlated individual photon counting method on a FluoTime200 (PicoQuant). The
excitation was provided using a 401 nm pulsed diode laser with repeating rates ranging
from 5.0 to 20 MHz. Photoluminescence was collected perpendicular to the excitation
and passed through a polarizer adjusted at the magic angle. The detection system consists
of a monochromator and a multi-channel base photomultiplier (Hamamatsu R3809U-50).
Lifetimes were obtained by fitting the fluorescence for a convolution of the instrument's
response function and a sum of exponentials using the FluoFit® software. The considered
residual plots and the chi-square (χ2) were used to accurately determine the quality of the
accessories during the analysis procedure.
Time resolved spectra were obtained by exciting the sample with a Nd:YAG laser
(EKSPLA), 10 Hz, 355 nm. Sample emission was directed onto a spectrograph and gated
iCCD camera (Stanford Computer Optics). The films were produced by spin coating on
quartz subtsrates.
Theoretical methods
Geometry optimizations of complexes C1-Se2 were carried out in vacuum, using
the Orca 4.0.1 software package41 at the DFT level using the PBE042,43 and the basis set
Def2-TZVP(-F) for all atoms.44–46 The calculations also included Grimme’s dispersion
correction with damping D3BJ47,48 and the RIJCOSX algorithm was employed to
accelerate the evaluation of the integrals, using the resolution of identity approximation
for the Coulomb part (RIJ), and the chain of spheres approach for the exchange
(COSX).49,50 RIJCOSX requires the specification of an auxiliary basis set for the
Coulomb part and a numerical integration grid for the exchange part, discussed elsewhere.
The vibrational frequencies for both complexes showed no imaginary frequencies. Time-
dependent density functional theory (TD-DFT) under Tamn-Dancoff approximation49
(TDA) was employed to obtain the first 50 singlet excited states, differing only on the
basis set chosen: ZORA-Def2-TZVP(-F) for all atoms, including ZORA relativistic
corrections.51,52To include solvent effects in the excited state energies, the conductor-like
polarizable continuum model53 (CPCM) was used, using acetonitrile as solvent.TD-
DFT/TDA was also employed to optimize the geometry of the first singlet excited state.

Journal of Materials Chemistry C
Page 22 of 25
View Article Online
DOI: 10.1039/D0TC03660A
The first triplet was optimized from the ground state of UKS calculation. The SOC on top
of the TD-DFT results were done by using quasi-degenerate perturbation theory.35,54 The
SOC integrals used here were calculated using a mean-field method named as RI-
SOMF(1X) and described elsewhere.55 The geometric representations of the complexes
were obtained using the Chemcraft program.56
ACKNOWLEDGEMENTS
The authors are grateful to CNPq, FINEP, CAPES, FAPESC, INCT-INEO,
PROPPI/UFOP (Nº 23109.004080/2019-88) and H2020-MSCA-RISE-2017 (OCTA,
#778158) for financial support of this work.
REFERENCES
1.
2.
F. Dumur, Org. Electro., 2015, 21, 27–39.
H. Xu, R. Chen, Q. Sun, W. Lai, Q. Su, W. Huang, X. Liu, Chem. Soc. Rev., 2014,
43, 3259–3302.
3.
4.
Y. Liu, C. Li, Z. Ren, S. Yan, M. R. Bryce, Nat. Rev. Mater., 2018, 3, 18020.
S. Wang, H. Zhang, B. Zhang, Z. Xie, W.-Y. Wong, Mater. Sci. Eng. R Rep., 2020,
140,100547.
5.
6.
7.
M. Hashimoto, S. Igawa, M. Yashima, I. Kawata, M. Hoshino, M. Osawa, J. Am.
Chem. Soc., 2011, 133, 10348–10351.
Y. Zhang, M. Schulz, M. Wächtler, M. Karnahl, B. Dietzek, Coord. Chem. Rev.,
2018, 356, 127–146.
L.-H. He, Y.-S. Luo, B.-S. Di, J.-L. Chen, C.-L. Ho, H.-R. Wen, S.-J. Liu, J.-Y.
Wang, W.-Y. Wong, Inorg. Chem., 2017, 56, 10311–10324.
Y. Liu, S.-C. Yiu, C.-L. Ho, W.-Y. Wong, Coord. Chem. Rev.,2018, 375, 514-557.
J. Nitsch, C. Kleeberg, R. Fröhlich, A. Steffen, Dalton Trans., 2015, 44, 6944–
6960.
8.
9.
10. D. J. Casadonte, D. R. McMillin, J. Am. Chem. Soc., 1987, 109, 331–337.
11. D. R. McMillin, J. R. Kirchhoff, K. V. Goodwin, Coord. Chem. Rev., 1985, 64,
83–92.
12. M. W. Blaskie, D. R. McMillin, Inorg. Chem., 1980, 19, 3519–3522.

Page 23 of 25
Journal of Materials Chemistry C
View Article Online
13. A. K. Ichinaga, J. R. Kirchhoff, D. R. McMillin, C. O. Dietrich-BuchecDkOeIr:,10P.1.03A9/.D0TC03660A
Marnot, J. P. Sauvage, Inorg. Chem., 1987, 26, 4290–4292.
14. H. Yersin, R. Czerwieniec, M. Z. Shafikov, A. F. Suleymanova, Phys. Chem.
Chem. Phys., 2017, 18, 3508–3535.
15. K. Zhang, D. Zhang, Spectrochim. Acta, 2014, 124, 341–348.
16. D. G. Cuttell, S.-M. Kuang, P. E. Fanwick, D. R. McMillin, R. A. Walton, J. Am.
Chem. Soc., 2002, 124, 6–7.
17. Q. Zhang, J. Chen, X.-Y. Wu, X.-L. Chen, R. Yu, C.-Z. Lu, Dalton Trans., 2015,
44, 6706–6710.
18. Y. Sun, V. Lemaur, J. I. Beltrán, J. Cornil, J. Huang, J. Zhu, Y. Wang, R. Fröhlich,
H. Wang, L. Jiang, G. Zou, Inorg. Chem., 2016, 55, 5845–5852.
19. L. Bergmann, J. Friedrichs, M. Mydlak, T. Baumann, M. Nieger, S. Bräse, Chem.
Commun., 2013, 49, 6501–6503.
20. R. Czerwieniec, J. Yu, H. Yersin, Inorg. Chem., 2011, 50, 8293–8301.
21. T. Hofbeck, U. Monkowius, H. Yersin, J. Am. Chem. Soc., 2015, 137, 399–404.
22. R. Hamze, J. L. Peltier, D. Sylvinson, M. Jung, J. Cardenas, R. Haiges, M.
Soleilhavoup, R. Jazzar, P. I. Djurovich, G. Bertrand, M. E. Thompson, Science,
2019, 363, 601.
23. M. Xie, C. Han, Q. Liang, J. Zhang, G. Xie, H. Xu, Sci. Adv., 2019, 5, eaav9857.
24. D. Liang, X.-L. Chen, J.-Z. Liao, J.-Y. Hu, J.-H. Jia, C.-Z. Lu, Inorg. Chem., 2016,
55, 7467–7475.
25. C. Murawski, K. Leo, M. C. Gather, Adv. Mater., 2013, 25, 6801–6827.
26. R. Czerwieniec, H. Yersin, Inorg. Chem., 2015, 54, 4322–4327.
27. X.-L. Chen, R. Yu, Q.-K. Zhang, L.-J. Zhou, X.-Y. Wu, Q. Zhang, C.-Z. Lu, Chem.
Mater., 2013, 25, 3910–3920.
28. R. Czerwieniec, M. J. Leitl, H. H. H. Homeier, H. Yersin, Coord. Chem. Rev.,
2016, 325, 2–28.
29. C. Bizzarri, F. Hundemer, J. Busch, S. Bräse, Polyhedron, 2018, 140, 51–66.
30. H. Yiersin, Wiley-VCH, 2018.
31. H. C. Braga, C. A. M. Salla, I. H. Bechtold, A. J. Bortoluzzi, B. de Souza, H.
Gallardo, Dyes Pigm., 2015, 117, 149–156.
32. C. A. M. Salla,; H. C. Braga, R. S. Heying,; J. Martins, W. Quirino, C. Legnani, B.
de Souza, A. J. Bortoluzzi, H. Gallardo, J. Eccher, I. H. Bechtold, Dyes Pig., 2017,
140, 343-353.

Journal of Materials Chemistry C
Page 24 of 25
View Article Online
DOI: 10.1039/D0TC03660A
33. Z. A. Siddique, Y. Yamamoto, T. Ohno, K. Nozaki, Inorg. Chem., 2003, 42, 6366–
6378.
34. G. Li, R. S. Nobuyasu, B. Zhang, Y. Geng, B. Yao, Z. Xie, D. Zhu, G. Shan, W.
Che, L. Yan, Z. Su, F. B. Dias, M. R. Bryce, Chem.-Eur. J., 2017, 23, 11761–
11766.
35. L-Y. Zou, Y-X. Cheng, Y. Li, H. Li H-X. Zhang, A-M. Ren, Dalton Trans., 2014,
43, 11252-11259.
36. B. de Souza, G. Farias, F. Neese, R. Izsák, J. Chem. Theory Comput., 2019, 15,
1896–1904.
37. R. Czerwinniec, M. J. Leitl, H. H. H.Homeier, H. Yersin, Coord. Chem. Rev. 325,
2016, 2-28.
38. APEX3 and SAINT and SADABS; Bruker AXS Inc.: Madison, WI, 2015.
39. G. M. Sheldrick, Acta. Crystallogr. C Struct. Chem., 2015, 71, 3–8.
40. A. L. Spek, Acta Crystallogr Sect D, Acta Crystallogr.D Biol. Crystallogr., 2009,
65, 148–155.
41. F. Neese, Software Update: Comput. Mol. Sci., 2018, 8, e1327.
42. J. P. Perdew, K. Burke, M. Ernzerhof, Phys. Rev. Lett., 1996, 77, 3865–3868.
43. J. P. Perdew, K. Burke, M. Ernzerhof, Phys. Rev. Lett., 1997, 78, 1396–1396.
44. A. Schäfer, H. Horn, R. Ahlrichs, J. Chem. Phys., 1992, 97, 2571–2577.
45. A. Schäfer, C. Huber, R. Ahlrichs, J. Chem. Phys., 1994, 100, 5829–5835.
46. F. Weigend, R. Ahlrichs, Phys. Chem. Chem. Phys., 2005, 7, 3297–3305.
47. S. Grimme, J. Antony, S. Ehrlich, H. Krieg, J. Chem. Phys., 2010, 132, 154104.
48. S. Grimme, S. Ehrlich, L. Goerigk, J. Comput. Chem., 2011, 32, 1456–1465.
49. R. Izsák, F. Neese, J. Chem. Phys., 2011, 135, 144105.
50. R. Izsák, F. Neese, W. Klopper, J. Chem. Phys., 2013, 139, 094111.
51. T. Petrenko, S. Kossmann, F. Neese, J. Chem. Phys., 2011, 134, 054116.
52. D. A. Pantazis, X.-Y. Chen, C. R. Landis, F. Neese, J. Chem. Theory Comput.,
2008, 4, 908–919.
53. A. V. Marenich, C. J. Cramer, D. G. Truhlar, J. Phys. Chem. B, 2009, 113, 6378–
6396.
54. B. de Souza, F. Neese, R. Izsák, J. Chem. Phys., 2018, 148, 034104.
55. F. Neese, J. Chem. Phys., 2005, 122, 034107.
56. Www.Chemcraftprog.Com.

Page 25 of 25
Journal of Materials Chemistry C
View Article Online
DOI: 10.1039/D0TC03660A
155x83mm (96 x 96 DPI)