Progress on photochromic diarylethenes with aggregation induced emission

Abstract

Among various photochromic compounds, diarylethenes (DAEs) have been widely studied and applied due to their excellent thermal bistability and fatigue resistance. Most researches are focused on the properties and applications of DAEs in solution. However, they meet the problem of fluorescence quenching at high concentration or at solid state which limits their performance in the practical applications. Fortunately, the DAE based photochromic aggregation-induced emission (AIE) materials do well in addressing this problem. This work here reviews the current research progress on the structures, properties and applications of the DAE based photochromic AIE materials and points out some existing problems so as to promote subsequent development of this field in the future.

Keywords

aggregation-induced emission (AIE) / photochromism / diarylethene (DAE) / fluorescence photoswitching / optical memory / super-resolution imaging

1 Introduction

With the increasing development of optical transmission systems toward longer distance, larger capacity and higher bit rate, forward error correction (FEC) becomes the first choice to improve the systems performance because the FEC can gain a many larger transmission distance and make the system more robust under worse conditions [1–5]. Therefore, the FEC technique has been used to compensate for the optical transmission quality degradation from noise and pulse distortion in optical transmission systems. The low density parity check (LDPC) code proposed by Gallager in 1962 is a kind of the linear block code based on sparse parity-check matrices [6]. The irregular LDPC code presented by Luby in 1977 turns out to be the most approximate to the Shannon limit [7,8], the performance of which is not only better than that of the regular ones, but also superior than that of Turbo codes.

As a channel with high signal noise ratio (SNR), optical fiber channel generally requires both the output error probability and redundancy to be quite low [2,9,10]. Owing to that, in this paper by analyzing the optical transmission systems as well as carrying out research on the construction algorithm of LDPC codes, a novel construction method of the regular LDPC codes and a LDPC(5929, 5624) code with low redundancy are proposed here. In addition, the simulation and the comparison analysis of the performance are also performed.

2 Construction methods of LDPC codes

The construction of parity-check matrices of LDPC codes cannot only determine their encode, but also play a crucial role in their decode. In particular, the various structures of LDPC codes result in sharp diversity on their implementation performance and their encoding/decoding complexity. Therefore, one of the research hot spots in recent years [2,7–10] has been concentrated on how to construct LDPC code types with excellent performance and low encoding/decoding complexity.

2.1 Construction principles of LDPC code

The main construction principles [2–5,10] of LDPC code types for optical transmission systems can be acquired as follows:

1) There ought to be low error floor or no error floor at best;

2) The net coding gain (NCG) should be high and the redundancy of the code type should be low;

3) The codeword length cannot be too long, the time delay arisen from encoding/decoding should not be too much, and the software/hardware implementation should be favorable, and so on.

In the meantime, in consideration of the analysis of the relative theories of high-bit-rate LDPC codes and the special characteristics of regular LDPC codes themselves, this paper also obey another two construction principles [2,10] as follows:

1) The LDPC codes constructed should have no four-cycle to suffice the requirements of Steiner limit, making the decoding of the LPDC code go with better decoding constringency;

2) The LDPC codes constructed should have lower density, that is, in the parity-check matrix of LDPC codes the number of ones should be absolutely less than that of zeros. In this way, there will be less calculation each time when iteratively decoding and the decoding complexity will be reduced.

2.2 Randomly construction method

There are a lot of random construction schemes, which are exemplified by several classical ones, including the method proposed by Gallager and Mackay [8,11]. The LDPC code constructed by Gallager [11] has the following characteristics: in the parity-check matrix BoldItalics of LDPC codes the numbers of ones of rows and columns (i, j) are all fixed and j is not less than three; the elements in the BoldItalic are randomly generated, together with all the numbers of ones in rows and columns evenly distributed; the parity-check matrix is vertically divided into j horizontal submatrices of the same size, each of which has its per column only containing a 1, and for the first submatrix ones in its ith row are only distributed in columns from (i-1)k + 1 to ik, and the rest of the submatrices are just randomly transformation from the first one; the class of this code type is a set randomly ranged with equal probability by the bottom j-1 columns of the matrix BoldItalic. Gallager ultimately reached the following conclusion: on the condition of the certain column heavy j, considerably low SNR and rather long code length, error probability of the optimum decoder decreases with code length rising. However, the defect in Gallager’s method is the possible appearance of four-cycle in the parity-check matrix of the LDPC code thus leading to descending of decoding performance.

As the parity-check matrix constructed via the construction method proposed by Gallager are generated randomly, owing to which the simple encoding as well as convenient decoding are not available to our application environment, especially in magnetic recording and optical communications, and other high-speed applications, this algorithm is unsuitable for the optical fiber communication system.

2.3 Systematically construction method

Gallager constructed LDPC codes randomly while Hösli and Erik used the construction methods of random LPDC codes presented by Gallager for reference, and proposed a method [12] to construct a kind of regular LPDC codes, which were called SCG(j, k) (systematically constructed Gallager (j, k) codes), where $j\in \left\{\mathrm{2},\mathrm{3},\mathrm{4}\right\}$ stands for the number of submatrices of the parity-check matrix and the column weight, and k is the fixed row weight of the parity-check matrix. SCG(j, k) codes can be determined uniquely by j and k, and for each SCG(j, k) code, the row number M and the column number N of the parity-check can be denoted by the following formula:

$$\begin{array}{ll}M=jk,\hfill & N=k^2\hfill \end{array}.$$

The minimum distance with no four-cycle [12] can be given by SCG(j, k) codes (when j = 2,3, k can be either an odd or an even, and when j = 4, k can only be an odd), this benefits for the research and analysis as well as the implementation of the hardware [12]. Each column in the j submatrices of the parity-check matrix of SCG(j, k) codes contains only one 1. For the first submatrix of SCG(4, k) code ones in its ith row are only distributed in columns from (i-1) k + 1 to ik, the second is the matrix is made up of a series of unit matrix and the first square matrix in the third one is a unit matrix with the back square matrix is a square which transforms from the front square with its column having one cyclic-shift, the first square matrix of the fourth is the mirror-image flip of the first square in the third in vertical center axis, similarly, the rest of the square is the mirror-image flip of the corresponding square in the third in same axis. SCG(2, k) code consists of two front submatrix taken from SCG(4, k) code while SCG(3, k) code is made up of the first three submatrix taken from SCG(4, k) code. Figure 1 shows an example of SCG(4, 5).

Fig.1 Check matrix of SCG(4, 5) code constructed by Hösli and Erik

Full size|PPT slide

3 Novel construction approach of LDPC codes

From the property [12] of SCG(j, k) code it can be seen that with the increment of the grouping length N the sparseness of the parity-check matrix of SCG(j, k) code will augment, which is convenient for reducing the decoding complexity in the case of long codeword length. For SCG(4, k) code in which k is an odd and k>4, the characteristics of the minimum distance is quite good, and it is easy to implement. Hence, SCG(4, k) code is more preferred in practical applications. Based on this, this paper on the foundation of systematically construction method raised by Hösli and Erik proposes a novel construction algorithm, which can expressed as follows: the fourth submatrix of SCG(4, k) code is a new form of the third in its reverse order. Then we will describe the scheme in detail.

As described in Section 2.3, SCG(4, k) is constructed on the basis of SCG(3, k), that is, the fourth submatrix of SCG(4, k) is transformed from the third one. Different submatrix is constructed in various transform methods, which is also directly determining the hardware store space and computational complexity in the future hardware application. Here, in this article we take the first three submatrix of the original SCG(4, k) code as those of the newly constructed parity-check matrix, and mark squares of the third submatrix from left to right in a order of standard serial number for: 0,1,2..., k-3, k-2, k-1. And the fourth submatrix is the reverse transformation of the third, namely the squares in the fourth submatrix is ranged in a order from left to right for the serial number: k-1, k-2, k-3,..., 2, 1, 0. Furthermore, label discrepancies between the third submatrix and the fourth:-(k-1), -(k-3),-(k-5),..., -2, 0, 2,..., k-5, k-3, k-1, which may be: 1,..., 2, 0, 2,..., k-3, k-1 after the mold k. It’s clearly seen that all the numbers on the left side of the symmetry axis that zero is taken as are odd when k (k>4) is odd, while all the numbers on the right are even after the mold k. Take the SCG(4, 5) as an example. Squares in the third parity-check submatrix of the SCG(4, 5)code are arranged in a order from left to right: 0,1,2,3,4, then that of the fourth submatrix is: 4,3,2,1,0. The label difference between the squares in the third submatrix and that in the fourth one are: -4,-2,0,2,4, take the value after the mold 5 for: 1, 3,0,2,4, obviously their value is different. Figure 2 depicts an example of SCG(4, 5) structured in the novel construction method.

Fig.2 Check matrix of SCG(4, 5) code constructed by Hösli and Erik

Full size|PPT slide

From Fig. 2, we can intuitively find no four-cycle. In addition, the related Matlab programming codes can also better verify the conclusion that there indeed exist no four-cycle in the parity-check matrix (especially applicable for k at a larger odd number.

4 Simulation results and performance analysis of novel LDPC code type

Since the encoding/decoding implementation complexity of the LDPC code on Galois Fields (GF)(2) is much simpler than that of employing the iterative concatenated code and Block Turbo Code (BTC) investigated, we choose GF(2), binary phase shift keying (BPSK) modulation and additive white Gaussian noise channel (AWGN) as the simulation environment where the Matlab programming codes of the parity-check matrix of SCG(4, k) code are also composed according to our novel construction approach. Meanwhile, in consideration of the demand of low redundancy in optical transmission system, the construction of LDPC codes, when k equals 77, is emphasized. From the simulation results, it’s clear that the LDPC code possess rank of 305, which not belongs a full one according to the property of SCG(4, k). That is to say, while there are three rows redundant in its parity-check matrix, the LDPC code has the information bit length of 5624 instead of 5621. Similarly, the corresponding LDPC code ought to be LDPC(5929, 5624) rather than LDPC(5929, 5621). Furthermore, the parity-check matrix of the LDPC code constructed using this algorithm introduces no four-cycle, which also matches the construction principles of LDPC code types for optical transmission systems.

Through simulation of the LDPC(5929, 5624) in the AWGN channel, we can get the relevant curve of bit error rate (BER) and bit SNR (Eb/No). Figure 3 shows the simulation results.

Fig.3 Simulation result diagram of novel LDPC(5929, 5624) code

Full size|PPT slide

In Fig. 3, analysis shows that the error correction performance of new constructed LDPC(5929, 5624) is obviously superior to the RS(255, 239). The NCG of LDPC(5929, 5624) is about 5.04 dB at BER of 10^-6, which is 1.60 dB higher than that of classical RS(255, 239) code; From the outer derivation to the curve in Fig. 3, there is an estimation that the NCG can achieve 7.18 dB at BER of 10^-12, 1.57 dB higher than that of RS(255, 239) code. Hence, the novel LDPC(5929, 5624) code with better error-correction performance and the low redundancy low of only 5.42% can better suitable for optical transmission systems.

To get sufficient contrast analysis, here we make a thorough comparison involving the LDPC(5929, 5624), the RS(255, 239) in ITU-T G 975 [13] and the two code types in ITU-T G 975.1 [14] which are simultaneously listed in Table 1, where the NCG performance and redundancy at BER of 10^-6 and 10^-12 are respectively revealed.

Tab.1 Comparison of error-correction performance between LDPC(5929, 5624) code and other code types

code type	redundancy/%	NCG at BER of 10-6/dB	NCG at BER of 10-12/dB
RS(255, 239)	6.69	3.44	5.61
BCH(3860, 3824) + BCH(2040, 1930)	6.69	4.70	7.98
RS(255, 239) + CSOC(k0/n0 = 6/7, J = 8)	24.48‚	4.81	7.95
LDPC(5929, 5624)	5.42	5.04	7.18

From Table 1, it can be seen that the redundancy of LDPC(5929, 5624) code is lower than those of RS(255, 239) code and BCH(3860, 3824) + BCH(2040, 1930) code. The NCG of LDPC(5929, 5624) is about 5.04 dB at BER of 10^-6, which is 1.60 dB higher than that of classical RS(255, 239) code and about 7.18 dB at BER of 10^-12, which is 1.57 dB higher than that of RS(255, 239) code. Therefore, the error correction performance of the novel LDPC code, compared with RS(255, 239) code and BCH(3860, 3824) + BCH(2040, 1930) code, is obviously better.

Furthermore, it’s very to draw the conclusion here after a careful comparison between Figs. 1 and 2. That is to say, the parity-check matrix of the fourth submatrix of SCG(4, k) code proposed in this paper consists of the reversion arrangements of the phalanxes of the third submatrix, while in the parity-check matrix of SCG(4, k) code proposed by Hösli and Erik when k is an odd, the phalanxes of the third and fourth submatrices are not identical, so in the future hardware implementation, the construction method can save hardware storage space and reduce the calculation complexity. Moreover, the decoding of the LDPC codes in the hardware can parallelly be implemented, so the decoding velocities of the two novel LDPC codes are very rapid, the complexities of implementing the two novel LDPC codes, compared with the BCH(3860, 3824) + BCH(2040, 1930) and RS(255, 239) + CSOC(k₀/n₀ = 6/7, J = 8) two concatenated codes in ITU-T G.975.1, are relatively lower, and the storing space can be saved and the computing complexity can be reduced in implementing the hardware in future. So the LDPC(5929, 5624) can be used as candidate super-FEC code type in optical transmission system and can better suit for high-speed ultra long-haul optical transmission systems.

5 Conclusions

An improved novel construction method of LDPC codes, based on the construction method of SCG(4, k), is proposed in this paper, where the fourth submatrix is constructed via the transformation from phalanxes of the third one in reverse order, in this way the storage space is saved and the calculation complexity is also reduced. The simulation analysis shows that the LDPC(5929, 5624) code constructed by the proposed method in this paper, compared with the classical RS(255, 239) code to be widely used in optical transmission system, has better error correction performances. As a result, the novel LDPC code has the advantages, such as better error correction performances, lower redundancy and lower decoding complexity to meet the requirements of optical transmission systems. So the LDPC(5929, 5624) can be used as candidate super-FEC code type in optical transmission system and can better suit for high-speed ultra long-haul optical transmission systems.

References

[1] Irie M, Mohri M. Thermally irreversible photochromic systems. Reversible photocyclization of diarylethene derivatives. Journal of Organic Chemistry, 1988, 53(4): 803–808

[2] Irie M. Diarylethenes for memories and switches. Chemical Reviews, 2000, 100(5): 1685–1716

[3] Irie M, Fukaminato T, Matsuda K, Kobatake S. Photochromism of diarylethene molecules and crystals: memories, switches, and actuators. Chemical Reviews, 2014, 114(24): 12174–12277

[4] Tian H, Chen B, Tu H Y, Müllen K. Novel bisthienylethene-based photochromic tetraazaporphyrin with photoregulating luminescence. Advanced Materials, 2002, 14(12): 918–923

[5] Li C, Liu J, Xie N, Yan H, Zhu M. Research progress on photoswitchable fluorescent dithienylethenes. Polymer Bulletin, 2015, (9): 142–162

[6] Li C, Chen Y, Xie N, Liu J, Fan C, Zhou Q, Zhu M. Research progress on hydrophilic photoswitchable fluorescent diarylethenes. Chinese Journal of Applied Chemistry, 2017, 34(12): 1379–1402

[7] Zou Y, Yi T, Xiao S, Li F, Li C, Gao X, Wu J, Yu M, Huang C. Amphiphilic diarylethene as a photoswitchable probe for imaging living cells. Journal of the American Chemical Society, 2008, 130(47): 15750–15751

[8] Li C, Hu Z, Aldred M P, Zhao L X, Yan H, Zhang G F, Huang Z L, Li A D Q, Zhu M Q. Water-soluble polymeric photoswitching dyads impart super-resolution lysosome highlighters. Macromolecules, 2014, 47(24): 8594–8601

[9] Pärs M, Hofmann C C, Willinger K, Bauer P, Thelakkat M, Köhler J. An organic optical transistor operated under ambient conditions. Angewandte Chemie, 2011, 50(48): 11405–11408

[10] Berberich M, Krause A M, Orlandi M, Scandola F, Würthner F. Toward fluorescent memories with nondestructive readout: photoswitching of fluorescence by intramolecular electron transfer in a diaryl ethene-perylene bisimide photochromic system. Angewandte Chemie, 2008, 47(35): 6616–6619

[11] Berberich M, Natali M, Spenst P, Chiorboli C, Scandola F, Würthner F. Nondestructive photoluminescence read-out by intramolecular electron transfer in a perylene bisimide-diarylethene dyad. Chemistry (Weinheim an der Bergstrasse, Germany), 2012, 18(43): 13651–13664

[12] Moreno J, Schweighöfer F, Wachtveitl J, Hecht S. Reversible photomodulation of electronic communication in a p-conjugated photoswitch-fluorophore molecular dyad. Chemistry (Weinheim an der Bergstrasse, Germany), 2016, 22(3): 1070–1075

[13] Szymański W, Beierle J M, Kistemaker H A V, Velema W A, Feringa B L. Reversible photocontrol of biological systems by the incorporation of molecular photoswitches. Chemical Reviews, 2013, 113(8): 6114–6178

[14] Pu S Z, Sun Q, Fan C B, Wang R J, Liu G. Recent advances in diarylethene-based multi-responsive molecular switches. Journal of Materials Chemistry C, Materials for Optical and Electronic Devices, 2016, 4(15): 3075–3093

[15] Li W B, Yao Q X, Sun L, Yang X D, Guo R Y, Zhang J. A viologen-based coordination polymer exhibiting high sensitivity towards various light sources. CrystEngComm, 2017, 19(4): 722–726

[16] Cai X, Zhu L, Bao S, Luo Q. Photochromic dithienylethene-branched triptycene hybrids. Dyes and Pigments, 2015, 121: 227–234

[17] Chen S, Yang Y, Wu Y, Tian H, Zhu W. Multi-addressable photochromic terarylene containing benzo[b]thiophene-1,1-dioxide unit as ethene bridge: multifunctional molecular logic gates on unimolecular platform. Journal of Materials Chemistry, 2012, 22(12): 5486–5494

[18] Andréasson J, Pischel U. Molecules with a sense of logic: a progress report. Chemical Society Reviews, 2015, 44(5): 1053–1069

[19] Roubinet B, Bossi M L, Alt P, Leutenegger M, Shojaei H, Schnorrenberg S, Nizamov S, Irie M, Belov V N, Hell S W. Carboxylated photoswitchable diarylethenes for biolabeling and super-resolution RESOLFT microscopy. Angewandte Chemie, 2016, 55(49): 15429–15433

[20] Roubinet B, Weber M, Shojaei H, Bates M, Bossi M L, Belov V N, Irie M, Hell S W. Fluorescent photoswitchable diarylethenes for biolabeling and single-molecule localization microscopies with optical superresolution. Journal of the American Chemical Society, 2017, 139(19): 6611–6620

[21] Giordano L, Jovin T M, Irie M, Jares-Erijman E A. Diheteroarylethenes as thermally stable photoswitchable acceptors in photochromic fluorescence resonance energy transfer (pcFRET). Journal of the American Chemical Society, 2002, 124(25): 7481–7489

[22] Irie M, Fukaminato T, Sasaki T, Tamai N, Kawai T. Organic chemistry: a digital fluorescent molecular photoswitch. Nature, 2002, 420(6917): 759–760

[23] Yun C, You J, Kim J, Huh J, Kim E. Photochromic fluorescence switching from diarylethenes and its applications. Journal of Photochemistry and Photobiology C, Photochemistry Reviews, 2009, 10(3): 111–129

[24] Li C, Yan H, Zhang G F, Gong W L, Chen T, Hu R, Aldred M P, Zhu M Q. Photocontrolled intramolecular charge/energy transfer and fluorescence switching of tetraphenylethene-dithienylethene-perylenemonoimide triad with donor-bridge-acceptor structure. Chemistry, an Asian Journal, 2014, 9(1): 104–109

[25] Li C, Yan H, Zhao L X, Zhang G F, Hu Z, Huang Z L, Zhu M Q. A trident dithienylethene-perylenemonoimide dyad with super fluorescence switching speed and ratio. Nature Communications, 2014, 5(1): 5709

[26] Sharnoff M. Photophysics of aromatic molecules: by John B. Birks (Wiley-Interscience, London, 1970) 704 pages, price 210 shillings. Journal of Luminescence, 1971, 4(1): 69–71

[27] Luo J, Xie Z, Lam J W Y, Cheng L, Chen H, Qiu C, Kwok H S, Zhan X, Liu Y, Zhu D, Tang B Z. Aggregation-induced emission of 1-methyl-1,2,3,4,5-pentaphenylsilole. Chemical Communications, 2001, (18): 1740–1741

[28] Mei J, Hong Y, Lam J W Y, Qin A, Tang Y, Tang B Z. Aggregation-induced emission: the whole is more brilliant than the parts. Advanced Materials, 2014, 26(31): 5429–5479

[29] Aldred M P, Li C, Zhang G F, Gong W L, Li A D Q, Dai Y, Ma D, Zhu M Q. Fluorescence quenching and enhancement of vitrifiable oligofluorenes end-capped with tetraphenylethene. Journal of Materials Chemistry, 2012, 22(15): 7515–7528

[30] Huang Z, Zhang X, Zhang X, Fu C, Wang K, Yuan J, Tao L, Wei Y. Amphiphilic fluorescent copolymers via one-pot combination of chemoenzymatic transesterification and RAFT polymerization: synthesis, self-assembly and cell imaging. Polymer Chemistry, 2015, 6(4): 607–612

[31] Tang B Z, Zhan X, Yu G, Sze Lee P P, Liu Y, Zhu D. Efficient blue emission from siloles. Journal of Materials Chemistry, 2001, 11(12): 2974–2978

[32] Shao A, Xie Y, Zhu S, Guo Z, Zhu S, Guo J, Shi P, James T D, Tian H, Zhu W H. Far-red and near-IR AIE-active fluorescent organic nanoprobes with enhanced tumor-targeting efficacy: shape-specific effects. Angewandte Chemie, 2015, 54(25): 7275–7280

[33] Zhang X Q, Chi Z G, Xu B J, Li H Y, Zhou W, Li X F, Zhang Y, Liu S W, Xu J R. Comparison of responsive behaviors of two cinnamic acid derivatives containing carbazolyl triphenylethylene. Journal of Fluorescence, 2011, 21(1): 133–140

[34] Mei J, Leung N L C, Kwok R T K, Lam J W Y, Tang B Z. Aggregation-induced emission: together we shine, united we soar! Chemical Reviews, 2015, 115(21): 11718–11940

[35] Lim S J, An B K, Jung S D, Chung M A, Park S Y. Photoswitchable organic nanoparticles and a polymer film employing multifunctional molecules with enhanced fluorescence emission and bistable photochromism. Angewandte Chemie, 2004, 43(46): 6346–6350

[36] Li C, Gong W L, Hu Z, Aldred M P, Zhang G F, Chen T, Huang Z L, Zhu M Q. Photoswitchable aggregation-induced emission of a dithienylethene-tetraphenylethene conjugate for optical memory and super-resolution imaging. RSC Advances, 2013, 3(23): 8967–8972

[37] Zhang X, Zhang X, Yang B, Hui J, Liu M, Chi Z, Liu S, Xu J, Wei Y. Novel biocompatible cross-linked fluorescent polymeric nanoparticles based on an AIE monomer. Journal of Materials Chemistry C, Materials for Optical and Electronic Devices, 2014, 2(5): 816–820

[38] Dong H, Luo M, Wang S, Ma X. Synthesis and properties of tetraphenylethylene derivatived diarylethene with photochromism and aggregation-induced emission. Dyes and Pigments, 2017, 139: 118–128

[39] Bunker C E, Hamilton N B, Sun Y P. Quantitative application of principal component analysis and self-modeling spectral resolution to product analysis of tetraphenylethylene photochemical reactions. Analytical Chemistry, 1993, 65(23): 3460–3465

[40] Aldred M P, Li C, Zhu M Q. Optical properties and photo-oxidation of tetraphenylethene-based fluorophores. Chemistry (Weinheim an der Bergstrasse, Germany), 2012, 18(50): 16037–16045

[41] Gong W L, Wang B, Aldred M P, Li C, Zhang G F, Chen T, Wang L, Zhu M Q. Tetraphenylethene-decorated carbazoles: synthesis, aggregation-induced emission, photo-oxidation and electroluminescence. Journal of Materials Chemistry C, Materials for Optical and Electronic Devices, 2014, 2(34): 7001–7012

[42] Jiang B P, Guo D S, Liu Y C, Wang K P, Liu Y. Photomodulated fluorescence of supramolecular assemblies of sulfonatocalixarenes and tetraphenylethene. ACS Nano, 2014, 8(2): 1609–1618

[43] Ou D, Yu T, Yang Z, Luan T, Mao Z, Zhang Y, Liu S, Xu J, Chi Z, Bryce M R. Combined aggregation induced emission (AIE), photochromism and photoresponsive wettability in simple dichloro-substituted triphenylethylene derivatives. Chemical Science (Cambridge), 2016, 7(8): 5302–5306

[44] Zhu L, Wang R, Tan L, Liang X, Zhong C, Wu F. Aggregation-induced emission and aggregation-promoted photo-oxidation in thiophene-substituted tetraphenylethylene derivative. Chemistry, an Asian Journal, 2016, 11(20): 2932–2937

[45] Belen’kii L I, Gromova G P, Kolotaev A V, Nabatov B V, Krayushkin M M. Synthesis and photochromic properties of tetrakis(3,5-dimethyl-2-thienyl)- and tetrakis(2,5-dimethyl-3-thienyl)ethylenes. Russian Chemical Bulletin, 2005, 54(5): 1208–1213

[46] Luo Q, Cao F, Xiong C, Dou Q, Qu D H. Hybrid cis/trans tetra-arylethenes with switchable aggregation-induced emission (AIE) and reversible photochromism in the solution, PMMA film, solid powder, and single crystal. Journal of Organic Chemistry, 2017, 82(20): 10960–10967

[47] Ma L, Wang S, Li C, Cao D, Li T, Ma X. Photo-controlled fluorescence on/off switching of a pseudo[3]rotaxane between an AIE-active pillar[5]arene host and a photochromic bithienylethene guest. Chemical Communications, 2018, 54(19): 2405–2408

[48] Chen S, Li W, Li X, Zhu W H. Aggregation-controlled photochromism based on a dithienylethene derivative with aggregation-induced emission. Journal of Materials Chemistry C, Materials for Optical and Electronic Devices, 2017, 5(10): 2717–2722

[49] Chen L, Zhang J, Wang Q, Zou L. Photo-controllable and aggregation-induced emission based on photochromic bithienylethene. Dyes and Pigments, 2015, 123: 112–115

[50] Su J, Fukaminato T, Placial J P, Onodera T, Suzuki R, Oikawa H, Brosseau A, Brisset F, Pansu R, Nakatani K, Métivier R. Giant amplification of photoswitching by a few photons in fluorescent photochromic organic nanoparticles. Angewandte Chemie, 2016, 55(11): 3662–3666

[51] Liu G, Zhang Y M, Zhang L, Wang C, Liu Y. Controlled photoerasable fluorescent behaviors with dithienylethene-based molecular turnstile. ACS Applied Materials & Interfaces, 2018, 10(15): 12135–12140

[52] Liu G, Zhang Y M, Xu X, Zhang L, Liu Y. Optically switchable luminescent hydrogel by synergistically intercalating photochromic molecular rotor into inorganic clay. Advanced Optical Materials., 2017, 5(11): 1700149

[53] Chung J W, Yoon S J, Lim S J, An B K, Park S Y. Dual-mode switching in highly fluorescent organogels: binary logic gates with optical/thermal inputs. Angewandte Chemie, 2009, 48(38): 7030–7034

[54] Sinawang G, Wang J, Wu B, Wang X, He Y. Photoswitchable aggregation-induced emission polymer containing dithienylethene and tetraphenylethene moieties. RSC Advances, 2016, 6(15): 12647–12651

[55] Lim S J, An B K, Park S Y. Bistable photoswitching in the film of fluorescent photochromic polymer: enhanced fluorescence emission and its high contrast switching. Macromolecules, 2005, 38(15): 6236–6239

[56] Singh R, Wu H Y, Kumar Dwivedi A, Singh A, Lin C M, Raghunath P, Lin M C, Wu T K, Wei K H, Lin H C. Monomeric and aggregation emissions of tetraphenylethene in a photo-switchable polymer controlled by cyclization of diarylethene and solvent conditions. Journal of Materials Chemistry C, Materials for Optical and Electronic Devices, 2017, 5(38): 9952–9962

[57] Tsivgoulis G M, Lehn J M. Photonic molecular devices: reversibly photoswitchable fluorophores for nondestructive readout for optical memory. Angewandte Chemie, 1995, 34(10): 1119–1122

[58] Fukaminato T, Doi T, Tamaoki N, Okuno K, Ishibashi Y, Miyasaka H, Irie M. Single-molecule fluorescence photoswitching of a diarylethene-perylenebisimide dyad: non-destructive fluorescence readout. Journal of the American Chemical Society, 2011, 133(13): 4984–4990

[59] Berberich M, Wurthner F. Terrylene bisimide-diarylethene photochromic switch. Chemical Science (Cambridge), 2012, 3(9): 2771–2777

[60] Berberich M, Krause A M, Orlandi M, Scandola F, Würthner F. Toward fluorescent memories with nondestructive readout: photoswitching of fluorescence by intramolecular electron transfer in a diaryl ethene-perylene bisimide photochromic system. Angewandte Chemie, 2008, 47(35): 6616–6619

[61] Fukaminato T, Doi T, Tamaoki N, Okuno K, Ishibashi Y, Miyasaka H, Irie M. Single-molecule fluorescence photoswitching of a diarylethene-perylenebisimide dyad: non-destructive fluorescence readout. Journal of the American Chemical Society, 2011, 133(13): 4984–4990

[62] Fernández-Suárez M, Ting A Y. Fluorescent probes for super-resolution imaging in living cells. Nature Reviews, Molecular Cell Biology, 2008, 9(12): 929–943

[63] Betzig E, Patterson G H, Sougrat R, Lindwasser O W, Olenych S, Bonifacino J S, Davidson M W, Lippincott-Schwartz J, Hess H F. Imaging intracellular fluorescent proteins at nanometer resolution. Science, 2006, 313(5793): 1642–1645

[64] Rust M J, Bates M, Zhuang X. Sub-diffraction-limit imaging by stochastic optical reconstruction microscopy (STORM). Nature Methods, 2006, 3(10): 793–796

[65] Yan J, Zhao L X, Li C, Hu Z, Zhang G F, Chen Z Q, Chen T, Huang Z L, Zhu J, Zhu M Q. Optical nanoimaging for block copolymer self-assembly. Journal of the American Chemical Society, 2015, 137(7): 2436–2439

[66] Huang B, Wang W, Bates M, Zhuang X. Three-dimensional super-resolution imaging by stochastic optical reconstruction microscopy. Science, 2008, 319(5864): 810–813

[67] Heilemann M, Dedecker P, Hofkens J, Sauer M. Photoswitches: key molecules for subdiffraction-resolution fluorescence imaging and molecular quantification. Laser & Photonics Reviews, 2009, 3(1–2): 180–202

[68] Zhu M Q, Zhang G F, Li C, Li Y J, Aldred M P, Li A D Q. Photoswitchable nanofluorophores for innovative biomaging. Journal of Innovative Optical Health Sciences, 2011, 04(04): 395–408

Acknowledgements

This work was supported by the National Basic Research Program (973) of China (Nos. 2015CB755602, and 2013CB922104), the National Natural Science Foundation of China (Grant Nos. 51673077, 51603078, and 21474034), the Fundamental Research Funds for the Central Universities (HUST: 2016YXMS029, HUST: 2018KFYXKJC033), the Nature Science Foundation of Hubei Province (2018CFB574) and Director Fund of WNLO (2016).

RIGHTS & PERMISSIONS

2018 Higher Education Press and Springer-Verlag GmbH Germany, part of Springer Nature