Unusual triplet-triplet annihilation in a 3D copper(i) chloride coordination polymer

Article abstract of DOI:10.1039/c9cp02891a

A new coordination polymer (CP) defined as [Cu₂Cl₂(EtS(CH₂)₄SEt)₄]_n (CP2) was prepared by reacting EtS(CH₂)₄SEt with CuCl in acetonitrile in a 1:2 stoichiometric ratio. The X-ray structure reveals formation of non-porous 3D material composed of parallel 2D-[Cu₂Cl₂S₂]_n layers of Cl-bridged Cu₂(μ-Cl)₂ rhomboids assembled by EtS(CH₂)₄SEt ligands. A weak triplet emission (Φ_e < 0.0001) is observed in the 400-500 nm range with τ_e of 0.93 (298 K) and 3.5 ns (77 K) as major components. CP2 is the only 2nd example of emissive thioether/CuCl-containing material and combined DFT/TDDFT computations suggest the presence of lowest energy M/XLCT excited states. Upon increasing the photon flux (i.e. laser power), a triplet-triplet annihilation (TTA) is induced with quenching time constants of 72 ps (k_Q = 1.3 × 10¹⁰ s^-1) and 1.0 ns (k_Q = 7.1 × 10⁸ s^-1) at 298 and 77 K, respectively, proceeding through an excitation energy migration operating via a Dexter process. Two distinct (I_o)^1/2 (I_o = laser power) dependences of the emission intensity are depicted, indicating saturation as the observed emission increases with the excitation flux. These findings differ from that previously reported isomorphous CP [Cu₂Br₂(μ-EtS(CH₂)₄SEt)₄]_n (CP1), which exhibits no TTA behaviour at 77 K, and only one (laser power)² dependence at 298 K. The ～18-fold increase in k_Q upon warming CP2 from 77 to 298 K indicates a temperature-aided TTA process. The significant difference between the presence (slower, CP2) and absence (CP1) of TTA at 77 K is explained by the larger unit cell contraction of the former upon cooling. This is noticeable by the larger change in inter-rhomboid Cu?Cu separation for CP2.

Full text of DOI:10.1039/c9cp02891a

PCCP
View Article Online
View Journal
PAPER
Unusual triplet–triplet annihilation in a 3D
copper(I) chloride coordination polymer†
Cite this:DOI: 10.1039/c9cp02891a
a
Adrien Schlachter,
Michael Knorr
Antoine Bonnot,a Daniel Fortin,a Paul-Ludovic Karsenti,a
b
a
and Pierre D. Harvey
*
A new coordination polymer (CP) defined as [Cu2Cl2(EtS(CH2)4SEt)4]n (CP2) was prepared by reacting
EtS(CH2)4SEt with CuCl in acetonitrile in a 1 : 2 stoichiometric ratio. The X-ray structure reveals formation
of non-porous 3D material composed of parallel 2D-[Cu2Cl2S2]n layers of Cl-bridged Cu2(m-Cl)2
rhomboids assembled by EtS(CH2)4SEt ligands. A weak triplet emission (Fe o 0.0001) is observed in the
400–500 nm range with te of 0.93 (298 K) and 3.5 ns (77 K) as major components. CP2 is the only
2nd example of emissive thioether/CuCl-containing material and combined DFT/TDDFT computations
suggest the presence of lowest energy M/XLCT excited states. Upon increasing the photon flux (i.e. laser
power), a triplet–triplet annihilation (TTA) is induced with quenching time constants of 72 ps (kQ = 1.3 Â
1010
s
À1) and 1.0 ns (kQ = 7.1 Â 108
s
À1) at 298 and 77 K, respectively, proceeding through an excitation
energy migration operating via a Dexter process. Two distinct (Io)1/2 (Io = laser power) dependences of the
emission intensity are depicted, indicating saturation as the observed emission increases with the excitation
flux. These findings differ from that previously reported isomorphous CP [Cu2Br2(m-EtS(CH2)4SEt)4]n (CP1),
which exhibits no TTA behaviour at 77 K, and only one (laser power)2 dependence at 298 K. The B18-fold
increase in kQ upon warming CP2 from 77 to 298 K indicates a temperature-aided TTA process. The significant
difference between the presence (slower, CP2) and absence (CP1) of TTA at 77 K is explained by the larger unit
cell contraction of the former upon cooling. This is noticeable by the larger change in inter-rhomboid CuÁÁÁCu
separation for CP2.
Received 21st May 2019,
Accepted 9th July 2019
DOI: 10.1039/c9cp02891a
rsc.li/pccp
light emission.30 Numerous 2-D31 and 3-D32 CPs were also
reported, including emissive porous33,34 and semi-porous
Introduction
Triplet–triplet annihilation (TTA) is an important photophysical networks.35,36 Recently, our groups reported the first CPs
process that attracts substantial attention nowadays in the fields (containing any d-block transition metal and any non-chromo-
of materials including metal–organic frameworks (MOFs),1,2 bio- phoric ligand) exhibiting a TTA process at 298 K for the
and therapeutic materials,3–5 solar cells,6–8 and organic light 3D-[(Cu2Br2){m-EtS(CH2)4SEt}]n CP (CP1, lemi
= 430 nm,
emitting devices.9 Organic polymeric materials are also prone te = 3.4 ns; Cu2Br2 exhibits a rhomboid structure).37 The drastic
for TTA processes,10–16 as well as some coordination polymers paucity of examples stems from the lack of favourable struc-
(CPs).2,17 In all cases, these materials invariably bear organic tures for triplet energy migration, which mainly relies on
chromophores (i.e. containing an extended p-system) as the the Dexter mechanism38 (double electron exchange).39–42 The
photo-active species. Recently, a large interest for CPs and necessary T1 energy migration for the TTA process in CP1 stems
related hybrids built upon copper(I) halide salts and dithioethers from a S-bridged (Cu2Br2)n layer securing connectivity between
was noticed throughout the literature.18 Indeed, CPs exhibiting the rhomboids, therefore the favourable orbital overlaps for the
thermal-19 and vapor-chromisms,20 redox properties,21 and anti- Dexter processes (through bond). So far, there is no evidence
43
proliferative activity22 were reported, but the major feature is their for a Forster process (through space). Curiously, the TTA
¨
quasi-omnipresent luminescence behavior,23–29 including white process in CP1 does not operate at 77 K, which is counter-
intuitive since upon cooling lattice contraction, orbital overlaps
a
´
´
´
Departement de chimie, Universite de Sherbrooke, Sherbrooke, Quebec, J1K 2R1,
should increase. Because TTA processes in CPs exhibiting no
chromophoric organic ligands are extremely rare, and to shed
light on this unexpected lack of TTA behavior at 77 K in CP1,
the obvious direction to seek answers is the case where X = Cl.
However, emissive CPs built upon CuCl/thioether are extremely
rare,31,32 where only one example has been reported so far,44
Canada. E-mail: Pierre.Harvey@USherbrooke.ca
b
´
´
Institut UTINAM UMR CNRS 6213, Universite Bourgogne Franche-Comte,
25030 Besançon, France. E-mail: michael.knorr@univ-fcomte.fr
† Electronic supplementary information (ESI) available: Complete detail of the DFT
and TDDFT computations of CP2. CCDC 1886279–1886287. For ESI and crystallo-
graphic data in CIF or other electronic format see DOI: 10.1039/c9cp02891a
This journal is ©the Owner Societies 2019
Phys. Chem. Chem. Phys.

View Article Online
Paper
PCCP
meaning that luminescence from such material is generally using a time correlated single photon counting (TCSPC) system
weak. We now report an emissive 3D-[(Cu2Cl2){m-EtS(CH2)4SEt}]n and the data were treated from both deconvolution by a multi-
CP featuring Cu(m2-Cl)2Cu rhomboids (CP2) as secondary building exponential analysis and by the exponential series method (ESM).
units (SBUs), which also exhibits TTA processes at 298 (fast) and The samples for powder XRD measurements were mixed with a
77 K (slow), meaning that the process is temperature-aided. The small amount of paratone oil, cut to approximately 0.3 Â 0.3 Â
presence of TTA for CP2 and not CP1 at 77 K is due to a larger 0.3 mm3, and placed on a sample holder mounted at 173.2 K on a
contraction of the unit cell.
Bruker APEX DUO X-ray diffractometer. Six correlated runs per
sample with Phi Scan of 360 degrees and exposure times of 270 s
were collected with the Cu micro-focus anode (1.54184 Å) and the
CCD APEX II detector at a 150 mm distance. These runs, from
À12 to À721 2y and 6 to 36o, were then treated and integrated
with the XRW2 Eval Bruker software to produce WAXD diffraction
patterns from 2.5 to 821 2y. The patterns were treated with
Diffrac.Eva version 2.0 from Bruker.
Experimental section
Material
All materials were purchased from Sigma-Aldrich and used
without any further purification.
Synthesis of ligand EtS(CH2)4SEt (L) was adapted from a
procedure reported by Hartley et al.45 In a flame dried 250 mL
round bottom flask under stirring, sodium (1.0 g, 43.5 mmol)
was dissolved in 110 mL absolute ethanol under an argon
atmosphere. Ethanethiol (3.2 mL, 43.5 mmol) was added and
the solution was stirred for 30 min, and after the solution was
refluxed. At this point, 1,4-dibromobutane (2.6 mL, 21.7 mmol)
was added dropwise and a white precipitate appeared. The
mixture was refluxed for one additional hour and filtered while
still hot. Ethanol was removed under reduced pressure. The
remaining oil was washed with water and extracted with
CH2Cl2. The oily residue was dissolved in hot ethanol and
stored at 5 1C in a refrigerator. White needles were recovered
Single crystal X-ray
A needle-like specimen of C4H9ClCuS, of approximate dimen-
sions 0.040 mm  0.100 mm  0.330 mm, was used for the
X-ray crystallographic analysis. The X-ray intensity data were
measured on a Bruker Kappa APEX II DUO CCD system equipped
with a TRIUMPH curved-crystal monochromator and a Mo fine-
focus tube (l = 0.71073 Å). Data collections have been carried out
at nine different temperatures – 100, 118, 137, 151, 168, 184, 217,
250 and 298 K using the same crystal. The lattice parameters were
obtained by least-squares fit to the optimized setting angles of the
entire set of collected reflections. Intensity data were recorded as
f and o scans with k offsets. No significant intensity decay or
temperature drift was observed during data collections. Data were
reduced by using DENZO software without applying absorption
corrections; the missing absorption corrections were partially
compensated by the data scaling procedure in the data reduction.
The structure was solved by direct methods with SIR92 program of
Altomare et al. Refinements were carried out by full-matrix least-
squares on F2 using SHELXL-97 program on the complete set of
reflections.46 All non-hydrogen atoms were refined with aniso-
tropic thermal parameters, whereas the H atoms were treated
using a riding model.
1
after one day. 3.0 g, 78%. NMR H d (ppm) 1.24 (t, 6H), 1.68
(m, 4H), 2.54 (m, 8 H). RMN 13C d (ppm) 14.91, 26.01, 28.80, 31.31.
Preparation of CP2 was adapted from a procedure reported
by Bonnot et al.37 In a Schlenk tube, CuCl (200 mg, 2.0 mmol)
was dissolved in degassed MeCN (10 mL) and L (375 mg,
2.1 mmol) was added. After stirring for 1 h, the green solution
was stored for one day in a refrigerator at 5 1C. Pale yellow
crystals of CP2 were formed progressively and separated after
two days by filtration. Yield (66%). Anal. calc. for C4H9ClCuS
(188.18): %C 25.53, %H 4.82, %S 17.04; found %C 25.28,
%H 4.96, %S 16.86.
Fast kinetic emission decay measurements
Instrumentation
The laser source was the SHG of a Solstice (Spectra Physics)
The NMR spectra were recorded on a Bruker Avance 300 Ti–sapphire laser (lexc = 398 nm; FWHM = 75–100 ps; pulse
Ultrashield NMR spectrometer. The chemical shifts are given energy = 0.1 mJ per pulse, rep. rate = 1 kHz; spot size B500 mm).
in ppm relative to the residual peaks of CDCl3. The thermal The IRF became of a HWHM of 8 ps after passing through the
analysis (TGA) traces were measured on a PerkinElmer TGA 7 optics. The detector was a Streak Camera (Axis-TRS, Axis Photo-
apparatus in the temperature range between 25 and 950 1C at a nique Inc.) with typically less than 8 ps resolution. Samples were
scanning rate of 10 1C minÀ1 under an argon atmosphere. The dispersed between two quartz plates. The results were also
solid-state UV-visible spectra were recorded on a Varian Cary globally analysed with the program Glotaran (http://glotaran.org)
300 Bio UV-vis spectrophotometer at 298 K using grazing-angle permitting to extract a sum of independent exponentials: I(l,t)
=
transmittance apparatus and a homemade 77 K sample-holder. C1(l) Â exp(Àt/t1) + C2(l) Â exp(Àt/t2) +.... The experiments using
Samples were dispersed between two quartz plates. Solid-State high laser power were performed to the limit of the thermal (or
emission, excitation, lifetimes were acquired on a phosphorimeter photochemical) stability of the samples. This stability was verified
FLS980 from Edinburgh Instruments equipped with single mono- by measuring the powder X-ray diffraction patterns.
chromators. Samples were introduced in a capillary and spectra
Computations
obtained were corrected for instrument response. The emission
lifetime measurements were performed using a nano-LED laser All density functional theory (DFT) and time-dependant (TD-
(lexc = 378 nm, 5 mW, fwhm = 90 ps). The lifetimes were obtained DFT) calculations were performed with Gaussian 1647 at the
Phys. Chem. Chem. Phys.
This journal is ©the Owner Societies 2019

View Article Online
PCCP
Paper
´
Universite de Sherbrooke with the Mammouth supercomputer and exceeds those for other CPs such as 1D [{Cu(m2-Cl)2Cu}-
´
´ ´
supported by Le Reseau Quebecois De Calculs Hautes Performances. (m2-medithiane)2]n (3.0517(8) Å) or 2D [{Cu(m2-Cl)2Cu}(m2-sec-
The .cif file from DRX structures has been used as optimized budithiane)2]n (2.8715(9) Å).65 These layers are held together
structure for calculations. The DFT (singlet and triplet energy states) by EtS(CH2)4SEt assembling ligands below and above these
as well as TD-DFT48–57 calculations were carried out using the B3LYP planes (Fig. 1c). The Cu2Cl2S4 rhomboids are centrosymmetric
method. VDZ (valence double z) with SBKJC effective core potentials (Fig. 1a), but the Cu–Cl and Cu–S bond lengths differ by B0.08
were used for all Cu and Br atoms58–63 and 3-21g* basis set was used and B0.05 Å, respectively, at 298 K. No phase-transition was
for C, H and S atoms.57 The calculated absorption spectra were noticed in the temperature range from 100 to 298 K.
obtained from GaussSum 3.0.64
The thermal stability was addressed by TGA (Fig. 2). The
traces are characterized by a first weight loss starting at
B175 1C and stopping at B230 1C to form a plateau with a
weight loss of 49.2%. Then, another weight loss starts near
400 1C and spreads all the way to 890 1C. The remainder
accounts for 11.3% of residual materials. This well-defined
TGA trace cannot straightforwardly be interpreted by sequential
ligand losses (i.e. EtSC4H8SEt (À47.4%), then Cl2 (À18.8%),
with ‘‘Cu2’’ (À33.8%) as residual; Table 1). Instead, the weight
losses are better explained by a decomposition of the dithioether
where one Et group remains in the solid (presumably captured by
a Cu atom) in exchange of one Cl atom. Then, volatile organo-
copper species are generated in the large 400–890 1C range. The
residual is most likely pure copper based on its characteristic
colour.
Results and discussion
Synthesis and characterization
CP2 was prepared by reacting 1,4-bis(ethylthio)butane with
CuCl in acetonitrile. Pale yellow air-stable crystals suitable for
X-ray structure determination grew upon standing (see ESI† for
the crystal data). The X-ray data of this material, which is
isostructural with CP1 (monoclinic, space group P21/n), reveal
the presence of a non-porous 3D CP (Fig. 1) built upon parallel
2D-[Cu2Cl2S2]n layers (Fig. 1b) of S-bridged Cu2Cl2 rhomboids.
Noteworthy, in contrast with most dithioether-assembled CPs
incorporating Cu(m2-X)2Cu SBUs, the rhomboids within the
layers are linked in a Cu ’ S - Cu mode, i.e. a S-atom acts
as a 4-electron donor implying a dative bonding using all two
non-bonding doublets. The very loose CuÁ Á ÁCu contact of
43.29 Å (Table S3, ESI†) excludes any intermetallic interactions
Photophysical properties
Prior to measurements on powder samples, the PXRD patterns
were systematically compared to the calculated one issued from
the single crystal X-ray data and the match was excellent in all
cases (Fig. 3, bottom).
The absorption, excitation and emission spectra of CP2 at
298 and 77 K are presented in Fig. 3 (top). The absorption
spectra are characterized by two maxima: B270 and B330 nm.
The interpretation of these bands has been made with the help
of DFT and TDDFT computations. The preparation of the input
file was executed by taking a CP fragment composed of 8 Cu2Cl2
rhomboid units directly extracted from the X-ray data and the
peripheral uncoordinated Cu atoms were then saturated by
EtSEt groups. These capping ligands were then optimized while
the central X-ray structure was non-optimized. The resulting
representations of the frontier MOs are provided for both the
Fig. 1 (a) One Cu2Cl2S4 rhomboid unit with bond distances (298 K, see
the ESI† for the uncertainties or Fig. 9 below). (b) Top view of a [Cu2Cl2S2]n
layer (s = short; l = long). (c) Side view of the 3D CP2 (the rectangle shows a
[Cu2Cl2S2]n layer). (d) and (e) Representations of one Cu2Cl2(EtS(CH2)4SEt)4
unit along the a, b and c axes.
Fig. 2 TGA trace (black) and its first derivative (grey) of CP2 under Ar
atmosphere in the range of 25 to 950 1C. Scan rate = 10 1C minÀ1
.
This journal is ©the Owner Societies 2019
Phys. Chem. Chem. Phys.

View Article Online
Paper
PCCP
Table 1 TGA data for CP2
[(Cu2Cl2)EtSC4H8SEt]n
M = 376.32 g molÀ1
(n = 1)
T range
(1C)
Exp.Dm Calc.Dm Proposed
(%)
(%)
assignment
175–230 À49.2
400–890 À39.5
890–950 À11.3
À49.1
À39.6
À11.3
EtSC4H8S + Cl
2/3Cu + Et + Cl
1/3Cu
Fig. 4 Representation of selected frontier MOs for CP2 for the singlet
state, H = HOMO, L = LUMO (see ESI† for more MOs); for the triplet state,
LSOMO and HSOMO are the lowest and highest semi-occupied molecular
orbitals, respectively. The energies are in eV.
Table 2 Calculated atomic contributions (in %) of the frontier MOs for
various fragments of CP2; LS = LSOMO, HS = HSOMO
HOMOÀ1
HOMO
LUMO
LUMO+1
Ligand
Cu
Cl
33.7
50.6
15.7
32.0
51.7
16.3
61.5
37.6
0.9
47.9
51.3
0.9
LSÀ1
LS
HS
HS+1
Ligand
Cu
Cl
37.7
49.2
13.1
34.0
50.3
15.7
60.1
33.3
6.6
61.3
37.9
0.8
Using TDDFT, the positions and oscillator strength ( f ) of the
first 50 spin-allowed (i.e. S0 - Sn; n 4 0) electronic transitions
were computed (detail placed in the ESI†). A bar graph reporting
the positions and the oscillator strength for each transition is
provided in Fig. 5. The bulk of these transitions are placed in
the 260–280 nm window. By assigning an arbitrary thickness of
500 cmÀ1 to each transition, a simulated spectrum is generated
(see solid line). The comparison of the bar graph and simulated
spectrum with the experimental data (see orange trace in Fig. 3,
top) is excellent and match perfectly the feature located at
B270 nm. This result permits to assign the remaining feature
at B 330 nm to spin-forbidden transitions (i.e. S0 - Tn; n 4 0).
Fig. 3 Top: Absorption (black), excitation (blue) and emission (red) spectra of
CP2 at 298 and 77 K. The orange bars represent the calculated positions of
the spin-allowed transitions (S0 - Sn) of CP2 by TDDFT (described below).
See Fig. 5 below for a larger scale. The orange curve is generated by assigning
and arbitrary thickness of 500 cmÀ1 to each transition. Bottom. Calculated
(red) and experimental (blue) powder X-ray diffraction patterns at 173 K for 2y
ranging from 51 to 501 for CP2. The calculated and measured diffraction
patterns match well, confirming the homogeneity of the crystalline phases.
Emission properties
CP2 is weakly emissive at both 298 and 77 K (Fig. 3, red traces).
This feature is in itself very rare as the only other example of
a thioether-based CuCl-containing material is the 2D-CP of
formula [(CuCl)(BzSCH2CRCCH2SBz)]n composed of polycyclic
[Cu6Cl6QCu6Cl6Q]n ribbons cross-linked by BzSCH2CRCCH2SBz
ligands.44 The emission quantum yield (Fe, at 298 K) of CP2 is very
low (i.e. below the detection limit of the integration sphere). Few
singlet and triplet states (Fig. 4) along with the calculated remarks are worthy. First, this observation is simply consistent
atomic contributions separated in Cu, Cl and thioether frag- with the fact that emissive CuCl/thioether-containing species are
ments (Table 2). By examining the change in these relative extremely rare, meaning that the paucity of examples is readily due
atomic contributions upon the HOMO - LUMO (singlet) and to intrinsic very low emission quantum yields in such materials.
LSOMO - HSOMO (triplet) transitions, these computations Second, the position of the emission band (i.e. in the 400–500 nm
predict that charge transfer excited states of the type (Cu2Cl2)- window, with a maximum in the vicinity of 420–435 nm) is in line
to-SRR’ are generated, often referred as M/XLCT.
with what is generally reported for the often more emissive
Phys. Chem. Chem. Phys.
This journal is ©the Owner Societies 2019

View Article Online
PCCP
Paper
Fig. 5 Representation of 50st electronic transitions calculated by TDDFT
of a fragment of CP2 (bar graph; f = computed oscillator strength). The
black line is generated by assigning a thickness of 500 cmÀ1 to each bar.
(H = HOMO, L = LUMO).
Cu2Br2S4 rhomboid-containing materials (i.e. 400 o lem
o
450 nm).18,66–69 Third, with an expected very low Fe value
(o0.0001), it is expected that the triplet excited state lifetime
(te) will also be short (as observed, see below). The te data is
generally encountered for the Cu2Br2S4 species are 0.6 o te o
66 ms,18,66–69 but no Fe data are available. For comparison
purposes, some strongly emissive (Cu2I2)m/thioether species
(m = 1, 2, 4) are also known with typical Fe values ranging
between 0.10 and 0.56, and exhibit te’s of 0.2 to 5.2 ms.36,70
Noteworthy, Cu2Br2S4-rhomboid-containing CP’s exhibiting te
in the short ns time scale are also known.71 Assuming that one
can transfer the radiative (kr) and non-radiative (knr) rate
Fig. 6 Emission decays of CP2 (blue), fit (red), IRF (black) and residual
(green) using a nano-LED laser (lexc = 378 nm; fwhm = 90 ps; power =
0.45 pJ) at 298 K (te1 {f%} = ‘‘0.03’’ ns {3.0}; te2 {f} = 0.93 ns {97.0},
w2 = 1.16) and 77 K (te1 {f%} = 1.0 ns {32.6}; te2 {f%} = 3.5 ns {67.4}, w2 = 1.06).
Note that this 0.03 ns value is not considered accurate due pulse width at
half-maximum of the excitation source and its relative intensity (see
footnote of Table 3).
constants from CuI- to CuBr- to CuCl-materials, qualitatively a Indeed, the graphs of Ie vs. (Io) is linear for the high-power region,
decrease in Fe by 3 orders of magnitude should proportionally whereas the low-power one is not (see ESI†). Additionally, the
result in a decrease in te as well (i.e. from ms to ns time scale). relative intensity of the short components (72 Æ 6 ps at 298 K
Experimentally, this is precisely what is observed (Table 3).
and B1.0 ns at 77 K; Streak camera) over their long ones (1.03 ns at
The emission decays (Fig. 6) are found bi-exponential 298 K and 3.5 ns at 77 K; Streak camera), i.e. Ie(short)/Ie(long),
(i.e. increasing the number of components to the decay analysis increases with the laser flux (Fig. 8; note that the decays are
did not reveal any significant new components and did not presented in semi-log format for convenience). Conclusively, the
improve the w2 significantly; moreover, upon higher laser power short component is the lifetime of the quenched species during the
two slopes in the log scale graphs were unambiguously observ- annihilation.
able; see Fig. 8 below). The presence of a TTA process was then
The emission quenching rates upon TTA, kQ, was evaluated
suspected (T1 + T1 - S0 + Tn + heat; then Tn - T1). using kQ = (1/te) À (1/te1)72 where te and te1 are respectively the
An investigation of the laser power dependence of the total quenched (72 ps (298 K); 1.0 ns (77 K)) and unquenched (1.0 ns
emission intensity and the relative intensity of both compo- (298 K); 3.5 ns (77 K)) components. These kQ values are 1.3 Â
nents was undertaken. Indeed, the total emission intensity (Ie) 1010 (298) and 7.1 Â 108 (77 K), indicating that the thermal
follows a linear trend with the square root of the laser intensity activation plays a role. Noteworthy, the former kQ value is fast
(I01/2; Fig. 7), thus demonstrating TTA. However, the graphs at and is precisely in the same order of magnitude to that reported
both temperatures show two regions (low- and high-power regions), for MOFs (B1010 À1; 298 K),73 and also compares favourably
s
thus indicate the presence of saturation in the high-power region. to that for CP1 37 (quenched component, te B 100 ps;
Table 3 Photophysical data for CP2 at minimal light flux
a
b
c
d
T (K)
lex (nm)
lem (nm)
fwhm (cmÀ1
)
Dfwhm (cmÀ1
)
te (ns)
w2
Fe
krd (105 sÀ1
)
knr (109 sÀ1
)
CP2
298
77
399
363
434
423
3600
3100
500
0.03, 0.93
1.02, 3.52
1.16
1.06
o0.0001
o1
B1.1
—
—
—
a
b
Dfwhm = (fwhm 298 K) À (fwhm 77 K); fwhm = full width at half-maximum. TCSPC data (Æ10%). The 0.03 ns value is not accurate due to its
relative intensity (B3%) and fwhm of the laser pulse (90 ps). A more accurate value was measured to be 72 Æ 6 ps using a streak camera and fs-laser
system (see below). Fe: emission quantum yield (detection limit B10À4) at 298 K. kr = Fe/te; knr = (1 À Fe)/te.
c
d
This journal is ©the Owner Societies 2019
Phys. Chem. Chem. Phys.

View Article Online
Paper
PCCP
Fig. 7 Graph of Ie vs. (laser power)1/2. Note that the powder XRD traces
before and after submitting the samples to laser irradiation were mea-
sured. All samples turned out stable using these laser flux conditions (Fig. 8,
bottom). The slopes of the low-power regions are 0.102 (298) and 0.086
(nJ1/2 À1
(77 K), which is consistent with the slower excitons (and kQ values)
)
at low temperature (see text).
unquenched component = 3.45 ns; i.e. kQ B 0.97 Â 1010
s
À1).
This fast rate may stem from the contribution of two mecha-
¨
nisms; Foorster and Dexter. However, the 77 K rate is signifi-
cantly slower (for CP2) and inexistent for CP1. Two new features
are observed for CP2: presence of a TTA at 77 K, and of two
regions in the (laser power)1/2 dependence on the emission
intensity, here due to saturation, is not observed for CP1.
Comparison with the [Cu2Br2(l-EtS(CH2)4SEt)4]n polymer (CP1)
Prior to present the X-ray study vs. temperature, a comparison
of the key parameters of both CPs is given (Table 4). The key
features are as follow: (1) the kQ values at 298 K are in the order
of 1010 À1, (2) at 77 K, the TTA process is either slow (CP2) or
s
too slow to be detected (CP1), and (3) for a 100 K temperature
lowering, the unit cell parameters experience a larger decrease
for CP2 (see detail in the ESI†) than for CP1 (see detail in the
ESI of ref. 37). The kQ values are, again, linked to the rate of
excitation energy migration, khop. At 298 K, the rates are in the
same order of magnitude for CP1 and CP2, which is consistent
with their isomorph structures. Upon lowering the tempera-
ture, the TTA process either slows down or stops, meaning that
the TTA is temperature-aided. However, this process is not
completely stopped in CP2, which is explained by the larger
unit cell contraction upon cooling. In addition, there is no
evidence for a two TTA zones (i.e. TTA and saturation) in the
graph of the emission intensity vs. (laser power)2 for CP1 at
298 K (as this is the case for CP2 in Fig. 7). The saturation
points where the lines curve between lower and higher laser
power zones for CP2 are B32 (nJ)1/2 (298 K) and B38 (nJ)1/2
Fig. 8 Top: Semi-log plots of the emission decay traces of CP2 at 298
and 77 K as a function of laser excitation intensity: Ie(short)/Ie(long) = 1.24
(750), 1.05 (1050), 1.78 (1200), 1.72 (1400), 1.85 (1650), and 1.92 (2000 mW)
at 298 K; 0.32 (450), 0.44 (600), 0.55 (750) 0.51 (900), 0.58 (1050), 0.58
(1200), 0.67 (1400) 0.65 (1600), 0.69 (1800), 0.69 (2000 mW). Bottom:
Comparison of the experimental powder XRD from 51 to 501 before and
after laser irradiation (i.e. before and after the measurements). The short
(72 Æ 6 ps) and long (1.03 Æ 0.10 ns) lifetimes at 298 K remain about
constant with the power.
Similarly, the Cu–S bond lengths increase with the temperature
and the slopes bond length vs. temperature, Dd(Cu–S)/DT, differ
somewhat. Concurrently, the Cu–Cl bonds behaves slightly differ-
ently where one bond exhibits a modest positive slope
(Dd(Cu–Cl2)/DT) while one remains constant (Dd(Cu–Cl1)/DT).
The reason for this stems from the dissymmetric dilatation of
the unit cell parameters with the temperature: +0.026(2),
+0.054(2) and +0.043(2) Å, respectively representing relative
increases of 0.29, 0.60 and 0.39%, for a, b, and c, from 100 to
(77 K). These values indicate that the migration processes (khop
)
are slower at 77 K, which is fully consistent with the trend
kQ (298 K) 4 kQ (77 K).
X-ray structure vs. temperature and interpretation of the TTA at
77 K (CP1 vs. CP2)
Expectedly, the unit cell volume and parameters a, b, and c 298 K (at 100 K, a = 8.9309, b = 6.7591, c = 10.8963 Å). The
expand, and the density decreases, with the temperature (ESI†). contraction of the unit cell parameters upon cooling CP1 and
Phys. Chem. Chem. Phys.
This journal is ©the Owner Societies 2019

View Article Online
PCCP
Paper
Fig. 9 Graph of the Cu–Cl and Cu–S bond lengths vs. temperature. The error bars are the uncertainties and the scalings are set identical for comparison
purposes; i.e. to stress the fact that the slopes are different. The atom numbering refers to Fig. 1.
Table 4 Comparison between CP1 and CP2 (tw = this work)
CP2 (X = Cl)tw
CP1 (X = Br)37
CP
Comment
TGA
T (K)
Tdec 4 175 1C
Tdec 4 211 1C
CP1 is more therm. stable
298
399
434
77
363
423
298
367
430
77
lexc (nm)
lem (nm)
te (minor)a
te (major)a
Fe
385
416
Common for rhomboids
b
b
0.03 ns 1.02 ns
—
—
0.93 ns 3.52 ns
3.45 ns 3.35 ns Not unusual for rhomboids
d
d
o0.0001
—
—
o0.0001
—
—
Not unusual for rhomboids
knr (108 sÀ1 c
)
B11
B2.9
d
d
TTA
Yes
72
Yes
Yes
B100
No
Based on linearity of Ie vs. (Io)1/2
d
Quenched comp. (ps)
B1000
—
—
Measured with a streak camera
kQ (sÀ1
Da (Å)
Db (Å)
)
B1010
0.020
0.048
0.037
B7 Â 108 B1010
1010 (298 K) is typical for TTA evidence for thermal activation
123 o T (K) o 293 for CP1
f
d
0.011
0.027
0.035
3.459(10) Å
118 o T (K) o 298 for CP2
Dc (Å) for a 170 K range
d(CuÁ Á ÁCu) at 293 K
CP2 contracts more than CP1 explaining the lack of TTA for CP1 at 77 K
In the Cu(m2-X)2 Cu rhomboids
3. 2903(10) Å
D(dCuÁ Á ÁCu) for a 170 K range 0.040 (Å)
0.032 (Å)
1
In the Cu–S–Cu bridges
Presence of exciton saturation or not
nb. of TTA mechanisms
2
2
0
a
TCSPC data at minimal light excitation flux. The 0.03 ns value for CP2 is not accurate due to its relative intensity (B3%; see caption of Table 3).
b
The short components are the quenched component due to TTA. These short components are not observed at minimal light flux, but at 298 K the
quenched component is observed with a value of B100 ps (Streak camera) with higher excitation power. Note that the larger knr value for CP2 is
c
consistent with the observation that emissive Cu–Cl CPs are extremely rare meaning that knr is large for these species. A lower rigidity of the Cu–Cl
d
e
f
framework appears to be responsible for the larger knr
the uncertainties kQ (CP1) o kQ (CP2).
.
Not accessible. No TTA process observed. Note that in absolute values not considering
CP2 within the same temperature range (here 170 K; Table 4) is that the TTA is temperature-driven. Noteworthy, thermally
larger for CP2, meaning that the shrinkage of some separations aided processes are also known for organics. For example, an
is more important for the latter. Indeed, the change in inter- increase in rate of excitation energy migration and singlet–
rhomboid distance, D(dCuÁÁÁCu), is larger for CP2, is one example singlet annihilation with the temperature for liquid benzene
(0.040 vs. 0.032 Å).
was reported over a decade ago.74 Moreover, CP1 does not
The slower kQ value (therefore khop) for CP2 and the absence exhibit a TTA, whereas CP2 does. The X-ray data indicate a
of TTA for CP1 (or too slow to be observed) at 77 K in larger unit cell contraction for CP2 for a same temperature
comparison with the faster kQ values at 298 K (1010
s
À1) indicate range. This larger shrinkage implies a larger decrease in bond
This journal is ©the Owner Societies 2019
Phys. Chem. Chem. Phys.

View Article Online
Paper
PCCP
distances and separations for CP2, thus promoting better Acknowledgements
conditions for excitation energy migration.
This research was supported by the Natural Sciences and
Engineering Research Council of Canada (NSERC).
During the course of this investigation, an unusual structural
feature was observed. Indeed, the intra-rhomboid CuÁÁÁCu separa-
tion appears to increase (very slightly) from 100 to 170 K, but
experiences a clear decrease (0.004 Å) going from 170 to 250 K
(ESI†). Considering the uncertainties, this feature is real, again
associated with the dissymmetry of the non-cubic 3D geometry
(Fig. 1). However, this change is so small (0.004 Å) that it bears no
consequence on the interpretation of the TTA processes, but is
worth noting.
References
1 Y. Zhang, D. Yang, J. Han, J. Zhou, Q. Jin, M. Liu and P. Duan,
Circularly Polarized Luminescence from a Pyrene-Cyclodextrin
Supra-Dendron, Langmuir, 2018, 34, 5821–5830.
´
2 R. Medishetty, J. K. Zareba, D. Mayer, M. Samoc and R. A.
Finally, attempts were also made to observe an emission
from upper states (T1 + T1 - S0 + Tn + heat or S0 + Sn + heat), but
stubbornly failed (note that the detection limit is B250 nm).
The reason most likely lies in the density of states located
nearby to each other (as well illustrated for the Sn in Fig. 5;
it is reasonably assumed that this is also true for the Tn states),
Fischer, Nonlinear optical properties, upconversion and
lasing in metal–organic frameworks, Chem. Soc. Rev., 2017,
46, 4976–5004.
3 L. Huang, E. Kakadiaris, T. Vaneckova, K. Huang,
M. Vaculovicova and G. Han, Designing next generation of
photon upconversion: Recent advances in organic triplet–
triplet annihilation upconversion nanoparticles, Biomaterials,
2019, 201, 77–86.
thus providing
a very large number of non-radiative
deactivation paths.
4 Q. Dou, L. Jiang, D. Kai, C. Owh and X. J. Loh, Bioimaging
and biodetection assisted with TTA-UC materials, Drug
Discovery Today, 2017, 22, 1400–1411.
Conclusion
5 M. Scholz and R. Dedic, Singlet Oxygen: Applications in
Biosciences and Nanosciences, 2016, vol. 2, pp. 63–81.
6 J. Pedrini and A. Monguzzi, Recent advances in the applica-
tion triplet–triplet annihilation-based photon upconversion
systems to solar technologies, J. Photonics Energy, 2017, 8, 1.
7 T. Dilbeck and K. Hanson, Molecular Photon Upconversion
Solar Cells Using Multilayer Assemblies: Progress and
Prospects, J. Phys. Chem. Lett., 2018, 9, 5810–5821.
8 Y. Shang, S. Hao, C. Yang and G. Chen, Enhancing Solar Cell
Efficiency Using Photon Upconversion Materials, Nano-
materials, 2015, 5, 1782–1809.
9 Q. Wei, N. Fei, A. Islam, T. Lei, L. Hong, R. Peng, X. Fan,
L. Chen, P. Gao and Z. Ge, Small-Molecule Emitters with
High Quantum Efficiency: Mechanisms, Structures, and
Applications in OLED Devices, Adv. Opt. Mater., 2018,
6, 1800512.
10 M. Aydemir, The contribution of triplet excitons to the total
singlet production yield in a sky-blue emitting co-polymer
film, Polym. Bull., DOI: 10.1007/s00289-019-02729-8.
11 P. Wang, Q. Huang, S. Zhao, Z. Qin, Z. Xu, D. Song and
B. Qiao, Investigating the evolution of excitons in polymer
light-emitting diodes by transient measurement, Org. Electron.,
2019, 68, 45–49.
12 A. Dey and D. Kabra, Role of Bimolecular Exciton Kinetics in
Controlling the Efficiency of Organic Light-Emitting Diodes,
ACS Appl. Mater. Interfaces, 2018, 10, 38287–38293.
13 S. Masoomi-Godarzi, M. Liu, Y. Tachibana, L. Goerigk,
K. P. Ghiggino, T. A. Smith and D. J. Jones, Solution-
Processable, Solid State Donor–Acceptor Materials for Sing-
let Fission, Adv. Energy Mater., 2018, 8, 1801720.
The isomorph CP1 and CP2 are still, to the best of our knowledge,
the only examples of CPs containing d-block transition metals and
non-chromophoric ligands that exhibit TTA processes. The parti-
cularity of the earlier work for CP1 (X = Br) was the absence of TTA
at 77 K, whereas at 298 K, the process is fast. The extension of the
past work to the case where X = Cl (CP2) was natural and helped
shining light on this curious result. The faster rate of TTA at 298 K
in comparison with that at 77 K indicates that the process is clearly
temperature-aided, which can also explain the absence of TTA for
CP1 at 77 K (i.e. too slow to be observed). The presence of a slow
TTA process for CP2 and not at all for CP1 at 77 K, is explained by
the significantly larger unit cell contraction upon lowering the
temperature to 77 K in CP2. The rates of emission quenching by
TTA, kQ, at 298 K (1.3 Â 1010 sÀ1 for CP2 and 0.97 Â 1010 sÀ1 for
CP1) compare favourably to other CPs containing organic ligands
(time scale B1010 À1) and are considered fast. This outcome stems
s
from the presence of strong MO couplings between the rhomboid
units (through bond) within the 2D-[Cu2Cl2S2]n layers as deduced
by DFT computations. Noteworthy, the duality has been reported
before for singlet energy transfer.75 Finally, the presence of two
regions (TTA and saturation) is observed for CP2 in the graph
emission intensity vs. (laser power)1/2. The fact that the saturation
point being is at higher power at 77 K is fully consistent with the
slower kQ values (i.e. which is related to khop) measured for this
temperature. All in all, the TTA is a common photophysical event to
all CPs and MOFs, regardless of the units that compose these
materials. This knowledge is useful for the design of new materials,
including with the hope of inducing observable upper energy
emissions, or simply converting into heat.
14 N. Chitraningrum, T. Y. Chu, P. T. Huang, T. C. Wen and
T. F. Guo, The triplet–triplet annihilation process of triplet
to singlet excitons to fluorescence in polymer light-emitting
diodes, Org. Electron., 2018, 62, 505–510.
Conflicts of interest
There are no conflicts to declare.
Phys. Chem. Chem. Phys.
This journal is ©the Owner Societies 2019

View Article Online
PCCP
Paper
15 T. Zhang, J. Sun, X. Liao, M. Hou, W. Chen, J. Li, H. Wang
and L. Li, Poly(9,9-dioctylfluorene) based hyperbranched
second ligating spacer variation: Increasing dimensionality
and macrocycle size, CrystEngComm, 2008, 10, 778–783.
copolymers with three balanced emission colors for 28 H. K. Tae, G. Park, W. S. Yong, K. M. Park, Y. C. Myong and
solution-processable hybrid white polymer light-emitting
devices, Dyes Pigm., 2017, 139, 611–618.
16 R. Andernach, H. Utzat, S. D. Dimitrov, I. McCulloch,
J. Kim, Self-assembled copper(I) complexes of symmetric
dithioether ligands, Bull. Korean Chem. Soc., 2008, 29,
499–502.
M. Heeney, J. R. Durrant and H. Bronstein, Synthesis and 29 R. Peng, D. Li, T. Wu, X. P. Zhou and W. N. Seik, Increasing
exciton dynamics of triplet sensitized conjugated polymers,
J. Am. Chem. Soc., 2015, 137, 10383–10390.
17 M. Hosoyamada, N. Yanai, K. Okumura, T. Uchihashi and
structure dimensionality of copper(I) complexes by varying
the flexible thioether ligand geometry and counteranions,
Inorg. Chem., 2006, 45, 4035–4046.
N. Kimizuka, Translating MOF chemistry into supramolecular 30 J. S. Ovens, P. R. Christensen and D. B. Leznoff, Designing
chemistry: Soluble coordination nanofibers showing efficient
photon upconversion, Chem. Commun., 2018, 54, 6828–6831.
18 P. D. Harvey and M. Knorr, Luminescent coordination
Tunable White-Light Emission from an Aurophilic CuI/AuI
Coordination Polymer with Thioether Ligands, Chem. – Eur. J.,
2016, 22, 8234–8239.
polymers built upon Cu4X4 (X = Br, I) clusters and mono- and 31 P. D. Harvey and M. Knorr, Stabilization of (CuX)n Clusters
dithioethers, Macromol. Rapid Commun., 2010, 31, 808–826.
19 T. H. Kim, Y. W. Shin, J. H. Jung, J. S. Kim and J. Kim,
Crystal-to-crystal transformation between three CuI coordi-
(X = Cl, Br, I; n = 2, 4, 5, 6, 8) in Mono- and Dithioether-
Containing Layered Coordination Polymers, J. Cluster Sci.,
2015, 26, 411–459.
nation polymers and structural evidence for luminescence 32 P. D. Harvey and M. Knorr, Designs of 3-Dimensional
thermochromism, Angew. Chem., Int. Ed., 2008, 47, 685–688.
20 J. Zhang, M. Li, L. Cheng and T. Li, Multifunctional poly-
mers built on copper–thioether coordination, Polym. Chem.,
2017, 8, 6527–6533.
Networks and MOFs Using Mono- and Polymetallic Copper(I)
Secondary Building Units and Mono- and Polythioethers:
Materials Based on the Cu–S Coordination Bond, J. Inorg.
Organomet. Polym. Mater., 2016, 26, 1174–1197.
21 M. Rasouli, M. Morshedi, M. Amirnasr, A. M. Z. Slawin and 33 A. Lapprand, A. Bonnot, M. Knorr, Y. Rousselin, M. M. Kubicki,
R. Randall, Synthesis, crystal structure, and electrochemical
properties of Cu(I) coordination polymers with two new
(NS)2 Schiff-base ligands containing long flexible spacers,
J. Coord. Chem., 2013, 66, 1974–1984.
D. Fortin and P. D. Harvey, Formation of an unprecedented
(CuBr)5 cluster and a zeolite-type 2D-coordination polymer: a
surprising halide effect, Chem. Commun., 2013, 49, 8848–8850.
34 S. Q. Liu, H. Konaka, T. Kuroda-Sowa, Y. Suenaga, H. Ito,
G. L. Ning and M. Munakata, Porous copper(I) complexes of
2,11-dithia[3.3]paracyclophane: desorption and adsorption
of guest molecules, Inorg. Chim. Acta, 2004, 357, 3621–3631.
22 D. Suresh, M. S. Balakrishna, K. Rathinasamy, D. Panda and
J. T. Mague, Large-bite bis(phosphite) ligand containing
mesocyclic thioether moieties: synthesis, reactivity, group
11 (CuI, AuI) metal complexes and anticancer activity studies 35 F. Juvenal, A. Langlois, A. Bonnot, D. Fortin and P. D. Harvey,
on a human cervical cancer (HeLa) cell line, Dalton Trans.,
2008, 2285.
Luminescent 1D- and 2D-Coordination Polymers Using CuX
Salts (X = Cl, Br, I) and a Metal-Containing Dithioether Ligand,
Inorg. Chem., 2016, 55, 11096–11109.
´
23 A. Raghuvanshi, C. Strohmann, J. B. Tissot, S. Clement,
A. Mehdi, S. Richeter, L. Viau and M. Knorr, Assembly of 36 A. Bonnot, F. Juvenal, A. Lapprand, D. Fortin, M. Knorr and P. D.
Coordination Polymers Using Thioether-Functionalized
Octasilsesquioxanes: Occurrence of (CuX)n Clusters (X = Br
and I) within 3D-POSS Networks, Chem. – Eur. J., 2017, 23,
16479–16483.
Harvey, Can a highly flexible copper(I) cluster-containing 1D and
2D coordination polymers exhibit MOF-like properties?, Dalton
Trans., 2016, 45, 11413–11421.
37 A. Bonnot, P. L. Karsenti, F. Juvenal, C. Golz, C. Strohmann,
D. Fortin, M. Knorr and P. D. Harvey, The 3D [(Cu2Br2){m-
EtS(CH2)4SEt}]n material: A rare example of a coordination
polymer exhibiting triplet–triplet annihilation, Phys. Chem.
Chem. Phys., 2016, 18, 24845–24849.
´
24 M. Chaabene, A. Khatyr, M. Knorr, M. Askri, Y. Rousselin
and M. M. Kubicki, Bis{(4-methylthio)phenylthio}methane
as assembling ligand for the construction of Cu(I) and Hg(II)
coordination polymers. Crystal structures and topological
(AIM) analysis of the bonding, Inorg. Chim. Acta, 2016, 451, 38 D. L. Dexter, A theory of sensitized luminescence in solids,
177–186. J. Chem. Phys., 1953, 21, 836–850.
25 L. Jiang, Z. Wang, S. Q. Bai and T. S. A. Hor, ‘Click-and- 39 X. Li and M. L. Tang, Triplet transport in thin films: funda-
click’-hybridised 1,2,3-triazoles supported Cu(I) coordina- mentals and applications, Chem. Commun., 2017, 53, 4429–4440.
tion polymers for azide–alkyne cycloaddition, Dalton Trans., 40 Q. Zhang, C. Zhang, L. Cao, Z. Wang, B. An, Z. Lin,
¨
2013, 42, 9437–9443.
R. Huang, Z. Zhang, C. Wang and W. Lin, Forster Energy
26 Y. Jin, H. J. Kim, J. Y. Lee, S. Y. Lee, W. J. Shim, S. H. Hong
and S. S. Lee, Hard/soft heterometallic network complex of a
Transport in Metal–Organic Frameworks Is Beyond Step-by-
Step Hopping, J. Am. Chem. Soc., 2016, 138, 5308–5315.
macrocycle with endo/exocyclic coordination, Inorg. Chem., 41 X. Jiang, X. Guo, J. Peng, D. Zhao and Y. Ma, Triplet–Triplet
2010, 49, 10241–10243.
27 W. J. Shi, C. X. Ruan, Z. Li, M. Li and D. Li, Tuning
framework formation by flexible ligand elongation and
Annihilation Photon Upconversion in Polymer Thin Film:
Sensitizer Design, ACS Appl. Mater. Interfaces, 2016, 8,
11441–11449.
This journal is ©the Owner Societies 2019
Phys. Chem. Chem. Phys.

View Article Online
Paper
PCCP
42 M. Oldenburg, A. Turshatov, D. Busko, S. Wollgarten, M. Adams,
density approximation ionization threshold, J. Chem. Phys.,
1998, 108, 4439–4449.
¨
N. Baroni, A. Welle, E. Redel, C. Woll, B. S. Richards and
I. A. Howard, Photon Upconversion at Crystalline Organic– 54 R. E. Stratmann, G. E. Scuseria and M. J. Frisch, An efficient
Organic Heterojunctions, Adv. Mater., 2016, 28, 8477–8482.
implementation of time-dependent density-functional theory
for the calculation of excitation energies of large molecules,
J. Chem. Phys., 1998, 109, 8218–8224.
¨
43 T. Forster, Zwischenmolekulare Energiewanderung und
Fluoreszenz, Ann. Phys., 1948, 437, 55–75.
44 A. Bonnot, M. Knorr, C. Strohmann, C. Golz, D. Fortin and 55 C. Lee, W. Yang and R. G. Parr, Development of the Colle-
P. D. Harvey, CuX (X = Cl, Br, I) Containing Coordination
Polymers Built Upon Isomeric RSCH2CRCCH2SR (R =
p-Tolyl, Benzyl) Dithioether Ligands: First Example of a
Salvetti correlation-energy formula into a functional of the
electron density, Phys. Rev. B: Condens. Matter Mater. Phys.,
1988, 37, 785–789.
Luminescent (CuCl)n/Dithioether Network, J. Inorg. Organo- 56 B. Miehlich, A. Savin, H. Stoll and H. Preuss, Results obtained
met. Polym. Mater., 2015, 25, 480–494.
with the correlation energy density functionals of becke and Lee,
45 F. R. Hartley, S. G. Murray, W. Levason, H. E. Soutter and
Yang and Parr, Chem. Phys. Lett., 1989, 157, 200–206.
C. A. McAuliffe, Systematics of palladium(II) and platinum(II) 57 A. D. Becke, Density-functional thermochemistry. III. The
dithioether complexes. The effect of ligand structure upon the role of exact exchange, J. Chem. Phys., 1993, 98, 5648–5652.
structure and spectra of the complexes and upon inversion at 58 J. S. Binkley, J. A. Pople and W. J. Hehre, Self-consistent
coordinated sulphur, Inorg. Chim. Acta, 1979, 35, 265–277.
46 G. M. Sheldrick, A short history of SHELX, Acta Crystallogr.,
Sect. A: Found. Crystallogr., 2008, 64, 112–122.
47 M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria,
M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone,
G. A. Petersson, H. Nakatsuji, X. Li, M. Caricato,
molecular orbital methods. 21. Small split-valence basis sets
for first-row elements, J. Am. Chem. Soc., 1980, 102, 939–947.
59 M. S. Gordon, J. S. Binkley, J. A. Pople, W. J. Pietro and
W. J. Hehre, Self-consistent molecular-orbital methods. 22.
Small split-valence basis sets for second-row elements,
J. Am. Chem. Soc., 1982, 104, 2797–2803.
A. V. Marenich, J. Bloino, B. G. Janesko, R. Gomperts, 60 W. J. Pietro, M. M. Francl, W. J. Hehre, D. J. DeFrees, J. A. Pople
B. Mennucci, H. P. Hratchian, J. V. Ortiz, A. F. Izmaylov,
J. L. Sonnenberg, D. Williams-Young, F. Ding, F. Lipparini,
F. Egidi, J. Goings, B. Peng, A. Petrone, T. Henderson,
and J. S. Binkley, Self-consistent molecular orbital methods.
24. Supplemented small split-valence basis sets for second-row
elements, J. Am. Chem. Soc., 1982, 104, 5039–5048.
D. Ranasinghe, V. G. Zakrzewski, J. Gao, N. Rega, 61 K. D. Dobbs and W. J. Hehre, Molecular orbital theory of the
G. Zheng, W. Liang, M. Hada, M. Ehara, K. Toyota,
R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima,
Y. Honda, O. Kitao, H. Nakai, T. Vreven, K. Throssell,
properties of inorganic and organometallic compounds 4.
Extended basis sets for third-and fourth-row, main-group
elements, J. Comput. Chem., 1986, 7, 359–378.
J. A. Montgomery, Jr., J. E. Peralta, F. Ogliaro, 62 K. D. Dobbs and W. J. Hehre, Molecular orbital theory of the
M. J. Bearpark, J. J. Heyd, E. N. Brothers, K. N. Kudin,
V. N. Staroverov, T. A. Keith, R. Kobayashi, J. Normand,
K. Raghavachari, A. P. Rendell, J. C. Burant, S. S. Iyengar,
properties of inorganic and organometallic compounds 5.
Extended basis sets for first-row transition metals,
J. Comput. Chem., 1987, 8, 861–879.
J. Tomasi, M. Cossi, J. M. Millam, M. Klene, C. Adamo, 63 K. D. Dobbs and W. J. Hehre, Molecular orbital theory of the
R. Cammi, J. W. Ochterski, R. L. Martin, K. Morokuma,
O. Farkas, J. B. Foresman and D. J. Fox, Gaussian 16,
Revision B.01, Gaussian, Inc., Wallingford CT, 2016.
properties of inorganic and organometallic compounds. 6.
Extended basis sets for second-row transition metals,
J. Comput. Chem., 1987, 8, 880–893.
48 P. Hohenberg and W. Kohn, Inhomogeneous Electron Gas, 64 N. M. O’boyle, A. L. Tenderholt and K. M. Langner, cclib:
Phys. Rev., 1964, 136, B864–B871.
A library for package-independent computational chemistry
49 W. Kohn and L. J. Sham, Self-Consistent Equations Including
algorithms, J. Comput. Chem., 2008, 29, 839–845.
Exchange and Correlation Effects, Phys. Rev., 1965, 140, 65 A. Raghuvanshi, M. Knorr, L. Knauer, C. Strohmann,
A1133–A1138.
S. Boullanger, V. Moutarlier and L. Viau, 1,3-Dithianes as
Assembling Ligands for the Construction of Copper(I) Coordina-
tion Polymers. Investigation of the Impact of the RC(H)S2C3H6
Substituent and Reaction Conditions on the Architecture of the
0D–3D Networks, Inorg. Chem., 2019, 58, 5753–5775.
50 R. G. Parr and W. Yang, Density-functional theory of atoms
and molecules, Oxford University Press, 1989.
51 The Challenge of d and f Electrons, ed. D. R. Salahub and
M. C. Zerner, American Chemical Society, Washington DC,
1989, vol. 394.
52 R. Bauernschmitt and R. Ahlrichs, Treatment of electronic
excitations within the adiabatic approximation of time
dependent density functional theory, Chem. Phys. Lett.,
1996, 256, 454–464.
53 M. E. Casida, C. Jamorski, K. C. Casida and D. R. Salahub,
Molecular excitation energies to high-lying bound states
from time-dependent density-functional response theory:
characterization and correction of the time-dependent local
66 P. D. Harvey and M. Knorr, Stabilization of (CuX)n Clusters
(X = Cl, Br, I; n = 2, 4, 5, 6, 8) in Mono- and Dithioether-
Containing Layered Coordination Polymers, J. Cluster Sci.,
2015, 26, 411–459.
67 P. D. Harvey and M. Knorr, Designs of 3-Dimensional Networks
and MOFs Using Mono- and Polymetallic Copper(I) Secondary
Building Units and Mono- and Polythioethers: Materials Based
on the Cu–S Coordination Bond, J. Inorg. Organomet. Polym.
Mater., 2016, 26, 1174–1197.
Phys. Chem. Chem. Phys.
This journal is ©the Owner Societies 2019

View Article Online
PCCP
Paper
68 M. Knorr, A. Khatyr, A. Dini Aleo, A. El Yaagoubi, C. Strohmann,
M. M. Kubicki, Y. Rousselin, S. M. Aly, D. Fortin, A. Lapprand
and P. D. Harvey, Copper(I) halides (X = Br, I) coordinated to
bis(arylthio)methane ligands: aryl substitution and halide
coordination polymers assembled by dithioethers ArS(CH2)
mSAr (Ar = Ph, p-Tol; M = 3, 5): Effect of the spacer length,
aryl group, and metal-to-ligand ratio on the dimensionality,
cluster, Inorg. Chem., 2012, 51, 9917–9934.
effects on the dimensionality, cluster size, and luminescence 72 P. D. Harvey, The Porphyrin Handbook: Multporphyrins,
properties of the coordination polymers, Cryst. Growth Des.,
2014, 14, 5373–5387.
Multiphthalocyanines and Arrays, Elsevier, 2012, vol. 18,
pp. 63–250.
69 A. Bonnot, M. Knorr, F. Guyon, M. M. Kubicki, Y. Rousselin, 73 M. Adams, M. Kozlowska, N. Baroni, M. Oldenburg, R. Ma,
C. Strohmann, D. Fortin and P. D. Harvey, 1,4-Bis-
(arylthio)but-2-enes as Assembling Ligands for (Cu2X2)n
(X = I, Br; n = 1, 2) Coordination Polymers: Aryl Substitution,
Olefin Configuration, and Halide Effects on the Dimension-
ality, Cluster Size, and Luminescence Properties, Cryst.
Growth Des., 2016, 16, 774–788.
D. Busko, A. Turshatov, G. Emandi, M. O. Senge, R. Haldar,
¨
C. Woll, G. U. Nienhaus, B. S. Richards and I. A. Howard, Highly
Efficient One-Dimensional Triplet Exciton Transport in a
Palladium–Porphyrin-Based Surface-Anchored Metal–Organic
Framework, ACS Appl. Mater. Interfaces, 2019, 11, 15688–15697.
74 H. Miyasaka and N. Mataga, Temperature Dependence of
Singlet Excitation Energy Migration in Liquid Benzene as
Revealed by Picosecond Laser Photolysis, Stud. Phys. Theor.
Chem., 1995, 83, 393–396.
70 A. Schlachter, L. Viau, D. Fortin, L. Knauer, C. Strohmann,
M. Knorr and P. D. Harvey, Control of Structures and
Emission Properties of (CuI)n 2-Methyldithiane Coordination
Polymers, Inorg. Chem., 2018, 57, 13564–13576.
71 M. Knorr, F. Guyon, A. Khatyr, C. Strohmann, M. Allain,
S. M. Aly, A. Lapprand, D. Fortin and P. D. Harvey, Con-
struction of (CuX)2n cluster-containing (X = Br, I; N = 1, 2)
75 S. Faure, C. Stern, R. Guilard and P. D. Harvey, Role of the
Spacer in the Singlet–Singlet Energy Transfer Mechanism
¨
(Forster vs. Dexter) in Cofacial Bisporphyrins, J. Am. Chem.
Soc., 2004, 126, 1253–1261.
This journal is ©the Owner Societies 2019
Phys. Chem. Chem. Phys.