Novel AuI polyynes and their high optical power limiting performances both in solution and in prototype devices

Article abstract of DOI:10.1039/c8tc01539b

Three novel Au^I polyynes have been prepared in high yield by copolymerization between an Au^I complex precursor and different ethynyl aromatic ligands. The investigation of their photophysical behavior has indicated that forming polyynes through polymerization not only maintains the high transparency of the corresponding Au^I polyynes similar to those of their corresponding small molecular Au^I acetylides, but also effectively enhances their triplet (T₁) emission ability. Critically, owing to their enhanced T₁ emission ability, all the Au^I polyynes exhibit a stronger optical power limiting (OPL) ability against a 532 nm laser than the corresponding small molecular Au^I acetylides. The Au^I polyynes based on fluorene and triphenylamine ligands show even better OPL performance than the state-of-the-art OPL material C₆₀, indicating their great potential in the field of laser protection. More importantly, in a prototype OPL device made by doping the fluorene-based Au^I polyyne into a polystyrene (PS) solid matrix, substantially improved OPL activity has been observed compared with that in the solution, demonstrating its great potential for practical application. All these results have provided a new strategy to achieve a balance between high OPL activity and good transparency for OPL materials, representing a valuable attempt towards developing new OPL materials with high performance to cope with the key problems in the field of nonlinear optics.

Full text of DOI:10.1039/c8tc01539b

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Nguyên T. K. Thanh, Xiaodi Su et al.
Fine-tuning of gold nanorod dimensions and plasmonic properties using
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DOI: 10.1039/C8TC01539B
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Novel AuI polyynes and their high optical power limiting
performances in both solution and prototype device†
Received 00th January 20xx,
Accepted 00th January 20xx
Zhuanzhuan Tian,a Xiaolong Yang ,a Boao Liu ,a Jiang Zhao,a Daokun Zhong,a Yong Wu,a Guijiang
Zhou,*a Wai-Yeung Wong b
DOI: 10.1039/x0xx00000x
Three novel AuI polyynes have been prepared in high yield by copolymerization between an AuI complex precursor and
different ethynyl aromatic ligands. The investigation of their photophysical behavior has indicated that forming polyynes
through polymerization not only maintains the high transparency of the concerned AuI polyynes similar to that of their
corresponding small molecular AuI acetylides, but also effectively enhances their triplet (T1) emission ability. Critically,
owing to their enhanced T1 emission ability, all the AuI polyynes can exhibit stronger optical power limiting (OPL) ability
against 532 nm laser than the corresponding small molecular AuI acetylides. The AuI polyynes based on fluorene and
triphenylamine ligands can show even better OPL performance than the state-of-the-art OPL material C60, indicating their
great potential in the field of laser protection. More importantly, in the prototype OPL device made by doping the
fluorene-based AuI polyyne into polystyrene (PS) solid matrix, substantially improved OPL activity has been observed
compared with that in the solution, demonstrating its great potential for practical application. All these results have
provided a new strategy to achieve the consistence between the high OPL activity and good transparency for OPL
materials, representing valuable attempt for developing new OPL materials with high performance to cope with the key
problems in the field of nonlinear optics.
www.rsc.org/
400-700 nm), transition metal polyynes can possess inherent
advantages as high performance OPL materials over the traditional
counterparts, such as fullerenes (e.g., C60),21,22 phthalocyanines
Introduction
Transition metal polyynes can be easily prepared by the cross-
coupling reaction between aromatic diacetylenes and divalent
transition metal ions, such as PtII, PdII and HgII ect.1-4 Owing to the
interaction between metal centers and organic acetylene ligands,
the unique properties have been afforded to the transition metal
polyynes. Hence, they can play critical roles in many fields, including
organic solar cells,5 organic light-emitting diodes (OLEDs),6-10 ion
sensors11 and nanomaterials12-15 and so on. Besides, the new PtII
acetylenes developed by Yang’s group can form novel molecular
skeletons and self-assembly structures, showing interesting
properties.16-19 More importantly, transition metal polyynes,
especially the ones with PtII centers, can show strong nonlinear
optical behaviors, such as optical power limiting (OPL) effect which
can be employed to protect human eyes or optical sensors from
the damages in the occasion of sudden exposure to intense laser
beams.20 Due to their high transparency in visible light region (ca.
(Pc),23,24 and porphyrins,25,26 since these traditional OPL materials
display poor transparency in visible-light region induced by their
large π-conjugated structures. It means that there is a conflict
between high OPL activity and good transparency for OPL materials,
representing a critical problem in the field of nonlinear optics to
restrain the practical application of traditional OPL materials.27
Hence, developing novel transition metal polyynes which can cope
with this problem should be of great importance in view of their
important applications.
Typically, only divalent transition metal ions can be possibly
employed to prepare polyynes through coupling with diacetylene
ligands. For example, PtII polyynes can represent the most
important transition metal polyynes ever reported. On the contrary,
AuI ions have been frequently employed to prepare small molecular
AuI acetylides.28-32 The AuI acetylides with aromatic diacetylene
ligands showing different electronic features have been successfully
prepared as advanced OPL materials possessing high
transparency.28 Furthermore, some of them can even outperform
C60 as novel OPL materials.28,29 Different from small molecules,
polymers can show unique properties. For instance, both PtII and
HgII polyynes can show different photophysical and OPL ability
compared with their corresponding small molecular PtII and HgII
acetylides.29 However, to the best of our knowledge, AuI polyynes
have been rarely reported in the literatures. Only Puddephatt’s
group had prepared three AuI polyynes in 1993.33 Unfortunately,
a.MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed
Matter, State Key Laboratory for Mechanical Behavior of Materials, Department
of Chemistry, School of Science, State Key Laboratory for Mechanical Behavior of
Materials, Xi’an Jiaotong University, Xi’an 710049, P. R. China.
E-mail: zhougj@mail.xjtu.edu.cn. Fax: +86-29-8266-3914
b.Department of Applied Biology and Chemical Technology, The Hong Kong
Polytechnic University, Hung Hom, Hong Kong, P. R. China.
†
Electronic supplementary information (ESI) available: Synthetic details for the
organic ligands, AuI acetylides and some photophysical data. See
DOI: 10.1039/x0xx00000x
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some of the AuI polyynes are insoluble in common organic solvents were estimated by using
Journal Name
a
calibration curve of polystyrene
and the research just concerns on synthesis without reported standards. The thermal gravimetric analysis (TGA) was performed
properties. Hence, the development of AuI polyynes is quite on METTLER TOLEDO TGA2 star system under nitrogen with a
desirable considering both basic photophysical investigations and heating rate of 20 K min-1.
applications.
On this basis, three novel AuI polyynes bearing organic acetylides
Optical power limiting measurements
Optical power limiting properties of the AuI polyynes were
with different structures have been prepared through employing a
precursor complex with two AuI centers connected by 1,4-
characterized by Z-scan measurements, which were performed at
bis(diphenylphosphino)benzene ligand. The basic photophysical
behaviors together with their OPL ability have been investigated.
For the first time, the triplet emission enhancement has been
observed in these soluble AuI polyynes. Importantly, the great
potential as new OPL materials has been found in these AuI
polyynes as well. The concerned results will not only provide
valuable photophysical and OPL information of these novel AuI
polyynes for developing new high-performance OPL materials, but
also present a new strategy for developing rarely explored AuI
polyynes.
532 nm for Gaussian mode laser beam with a repetition rate of 20
Hz from a Q-switched Quantel Q-Smart 100 Nd:YAG laser. The laser
beam was split into two beams by a beam splitter. One was used as
the reference beam, which was received by a power detector (D1),
the other was focused with a lens (f = 25 cm) for the sample
measurement. After transmitting through the sample, the light
beam entered another power detector (D2). The sample to be
measured was moved automatically along a rail to change the
incident irradiance on it. The incident and transmitted powers were
detected simultaneously by the two power detectors D1 and D2
individually. The OPL performance of each of the solution samples
in CH2Cl2 was measured in a 1 mm quartz cell. The prototype device
is prepared by casting the polystyrene (PS) solution (0.2 g mL-1) in
CH2Cl2 with ca. 3.0-wt% doping level of P-Au-FLU into a PTFE mode.
Then, it was left on a clean bench for 3 days at 298 K to obtain the
solid plate as prototype OPL device.
Experimental
General information
The commercially available reagents were used directly as received.
All reactions were proceeded under a nitrogen atmosphere. The
solvents were purified by standard methods under dry nitrogen
prior to use. The reactions were monitored by thin-layer
chromatography (TLC) with Merck pre-coated aluminum plates.
Flash column chromatography and preparative TLC were carried out
using silica gel. All Sonogashira reactions were carried out with
Schlenk techniques under a nitrogen atmosphere.
Computational details
Geometrical optimizations were conducted using the popular B3LYP
density functional theory (DFT). The basis set used for C, H, O, N
and P atoms was 6-311G(d, p), whereas effective core potentials
with a LanL2DZ basis set were employed for Au atom.35,36 The
energies of the excited states of the complexes were computed by
TD-DFT based on all the ground-state geometries. All calculations
were carried out by using the Gaussian 09 program.37
Physical measurements
1H-, 13C- and 31P-NMR spectra were measured in CDCl3 solvent with
1
a Bruker AXS 400MHz NMR spectrometer with the H and 13C NMR
Synthesis
chemical shifts quoted relative to SiMe4 and the 31P chemical shifts
relative to the 85% H3PO4 external standard. Fast atom
bombardment (FAB) mass spectra for characterizing the molecular
weight of the small molecular compounds were recorded on a
Finnigan MAT SSQ710 system. UV-vis spectra were recorded with a
The ethynyl aromatic ligands were prepared by the typical
Sonogashira coupling reaction.7-9 All the synthetic procedures are
provided in the Electronic Supplementary Information (ESI).
General synthetic procedure for the AuI polyynes
PerkinElmer
Lambda
950
spectrophotometer.
The
Under N2 atmosphere, L-2Au (1.0 equiv) was added to the solution
of the corresponding diethynyl aromatic ligand (1.0 equiv) in
CH2Cl2/MeOH (v:v = 2:1). Then, NaOH (1.1 equiv) in MeOH solution
(0.1 M) was added. The reaction mixture was stirred for 10 h at
room temperature. After removing the solvent, the residue was
dissolved in small amount of CH2Cl2 and filtered by a syringe filter
(PTFE, 0.45 μm) to remove the insoluble part. Then, it was
precipitated in MeOH and the precipitation was repeated for two
times. The AuI polyynes were obtained in high yield as off-white
solid.
photoluminescent (PL) properties of the AuI polyynes were
measured with an Edinburgh Instruments FLS920 fluorescence
spectrophotometer. The lifetimes for the excited states were
measured by
a single photon counting spectrometer from
Edinburgh Instruments FLS920 with a 360 nm picosecond LED lamp
as the excitation source, while those at 77 K were obtained with the
excitation from a Xenon flash lamp. The PL spectra and lifetimes at
77 K were obtained by dipping the degassed CH2Cl2 solution in a
thin quartz tube into liquid nitrogen Dewar and recording the data
after standing 3 minutes. The fluorescent quantum yields (ΦF) were
determined in CH2Cl2 solutions at 298 K against quinine sulfate in
1.0 M H2SO4 (ΦF ca. 0.56).30 Phosphorescence quantum yields (ΦP)
were measured at room temperature with an integrating sphere
from Edinburgh Instruments FLS920 with excitation wavelength at
340 nm. The molecular weights of these AuI polyynes were
determined by Waters 2695 GPC in CHCl3. The molecular weights
P-Au-FLU: (Yield: 86%). 1H NMR (400 MHz, CDCl3):
δ (ppm) 7.63-7.44
(m, 30H, Ar), 1.88 (br, 4H, –CH2–), 1.22-0.86 (m, br, 36H, –CH2–),
0.86 (t, 6H, –CH3), 0.54 (br, 4H, –CH2–); 31P NMR (161.9 MHz, CDCl3):
δ
(ppm) 42.44; GPC: Mn = 2.0 × 104 g mol-1, PDI = 1.9 (against
polystyrene standards); Anal. Found: C 60.96, H 5.68.
2 | J. Name., 2012, 00, 1-3
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P-Au-TPA: (Yield: 85%). 1H NMR (400 MHz, CDCl3):
7.49 (m, 24H, Ar), 7.33 (d, 4H, Ar), 7.03 (d, 2H, Ar), 6.89 (d, 4H, Ar), CH3 ); 31P NMR (161.9 MHz, CDCl3):
δ
(ppm) 7.58- ), 1.84-1.80 (m, 2H, –CH2–), 1.52-1.23 (m, 18H, –CH2–), 0.88 (t, 3H, –
(ppm) 42.46; GPC: Mn = 1.6 ×
δ
6.82 (d, 2H, Ar), 3.92 (br, 2H, –OCH2–), 1.76 (br, 2H, –CH2–), 1.51- 104 g mol-1, PDI = 1.9 (against polystyrene standards); Anal. Found:
1.26 (m, br, 18H, –CH2–), 0.87 (s, br, 3H, –CH3); 31P NMR (161.9 C 56.73, H 4.33, N, 1.01.
MHz, CDCl3):
δ
(ppm) 42.42; GPC: Mn = 1.8 × 104 g mol-1, PDI = 2.1
(against polystyrene standards); Anal. Found: C 57.93, H 4.56, N,
Results and discussion
1.21.
P-Au-CAZ: (Yield: 89%). 1H NMR (400 MHz, CDCl3):
δ (ppm) 8.21 (br,
Synthesis and structural characterization
2H, Ar), 7.62-7.50 (m, 26H, Ar), 7.24 (d, 2H, Ar), 4.20 (t, 2H, –NCH2–
Scheme 1 Synthesis of the AuI polyynes.
The limitation of monovalent ion AuI for synthesis of polyynes polyynes just like the well explored PtII-based polyynes.
comes from the fact that it can only couple with one acetylene Inspired by the complex precursor Ph3PAuCl employed to
group. Obviously, obtaining complex precursor with two AuI prepare small molecular AuI acetylides, dinuclear L-2Au have
centers should afford the opportunity to prepare AuI-based been designed and prepared (Scheme 1). In L-2Au, two Au–Cl
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