Tuning the solid-state emission of small push-pull dipolar dyes to the far-red through variation of the electron-acceptor group

Article abstract of DOI:10.1016/j.dyepig.2018.03.049

Series of solid-state emitters based on the D-π-A dipolar structure and featuring various electron-donor and electron-acceptor groups were designed, and their spectroscopic properties studied. From weak emission in dilute solutions, intense emissions in aggregated state (AIE) and in the crystalline state were obtained. Analysis in light of crystal structures obtained by X-ray diffraction revealed specific crystal packing and presence of long chain of emitting aggregates. This simple molecular engineering around the D-π-A dipolar structure provides easy access to a wide range of effective solid-state emitters allowing modulation of emission wavelengths up to the near infrared (λ_em reaching 735 and 768 nm for compound 2f and 3f bearing the strongest electron-withdrawing group).

Full text of DOI:10.1016/j.dyepig.2018.03.049

Accepted Manuscript
Tuning the solid-state emission of small push-pull dipolar dyes to the far-red through
variation of the electron-acceptor group
Sébastien Redon, Gwenaëlle Eucat, Martin Ipuy, Erwann Jeanneau, Isabelle Gautier-
Luneau, Alain Ibanez, Chantal Andraud, Yann Bretonnière
PII:
S0143-7208(18)30415-7
10.1016/j.dyepig.2018.03.049
DYPI 6634
DOI:
Reference:
To appear in: Dyes and Pigments
Received Date: 20 February 2018
Revised Date: 22 March 2018
Accepted Date: 23 March 2018
Please cite this article as: Redon Sé, Eucat Gwenaë, Ipuy M, Jeanneau E, Gautier-Luneau I, Ibanez
A, Andraud C, Bretonnière Y, Tuning the solid-state emission of small push-pull dipolar dyes to the
far-red through variation of the electron-acceptor group, Dyes and Pigments (2018), doi: 10.1016/
j.dyepig.2018.03.049.
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Tuning the Solid-State Emission of Small Push-pull
Dipolar Dyes to the Far-red Through Variation of the
Electron-acceptor Group
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Sébastien Redon,a Gwenaëlle Eucat,,a,b Martin Ipuy,a Erwann Jeanneau,c Isabelle Gautier-Luneau,b
Alain Ibanez,b Chantal Andraud*,a and Yann Bretonnière*,a
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a Univ Lyon, ENS de Lyon, CNRS UMR 5182, Université Lyon 1, Laboratoire de Chimie, F-69342
Lyon (France).
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b Univ. Grenoble Alpes, Institut Néel, F-38042 Grenoble (France).
CNRS, Institut Néel, F-38042 Grenoble (France).
Institute of Engineering, Univ. Grenoble Alpes
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c Centre de Diffractométrie Henri Longchambon, Université Lyon I, 43 boulevard du 11 Novembre
1918, F-69622 Villeurbanne Cedex (France).
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chantal.andraud@ens-lyon.fr / yann.bretonniere@ens-lyon.fr
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RECEIVED DATE (to be automatically inserted after your manuscript is accepted if required
according to the journal that you are submitting your paper to)
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Abstract
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Series of solid-state emitters based on the D-π-A dipolar structure and featuring various electron-donor
and electron-acceptor groups were designed, and their spectroscopic properties studied. From weak

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emission in dilute solutions, intense emissions in aggregated state (AIE) and in the crystalline state were
obtained. Analysis in light of crystal structures obtained by X-ray diffraction revealed specific crystal
packing and presence of long chain of emitting aggregates. This simple molecular engineering around
the D-π-A dipolar structure provides easy access to a wide range of effective solid-state emitters
allowing modulation of emission wavelengths up to the near infrared (λem reaching 735 and 768 nm for
compound 2f and 3f bearing the strongest electron-withdrawing group).
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Highlights
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Library of small push-pull dipolar solid-state emitters has been obtained featuring three different
electron-donor groups and various electro-acceptor groups.
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New electron-acceptor groups based on substituted 2(5H)-furanone rings are presented.
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Fluorescence properties in the aggregated state and in the solid-state are described, and
correlated to the presence of specific aggregates in the crystal structure.
The best dyes displayed near-infrared emission in the solid-state with emission quantum yield of
11% at λem=735 nm and 4% at λem=768 nm.
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Keywords
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Solid-state fluorescence; Push-pull dyes; Organic dyes; Near-infrared; Aggregation-induced emission;
2(5H)-furanone rings
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1. Introduction
Engineering around organic solid-state emitters has become a thriving area of research these last few
years, impelled by potential applications in the field of optoelectronics, materials and bio-imaging.[1-4]
In that particular context, fluorescent organic nanocrystals or emissive organic nanoparticles based on
fluorophores displaying aggregation-induced emission (AIE) properties are a promising alternative to
dissolved fluorophores or to inorganic quantum dots.[5, 6] Advantages include higher absorption and
higher photo-stability, combined to the infinite possibilities offered by organic synthesis to functionalize
the dye and to tune the spectroscopic properties. In particular, shifting the emission wavelength towards
the far-red and even the near infrared (NIR) in the first biological transparency window (λem>650 nm) is
a requisite for deeper in-vivo imaging.[7-10] This wavelength range allows enhanced penetration depth
and better contrast compared to the visible, due to lower absorption, minimized scattering and lower
self-fluorescence from biological samples. However so far, good solid-state fluorophores with far-red /
NIR emissions are still scarce despite increasing number of structures available and a tremendous work
on AIE-active fluorophore design.[5, 11] On the one hand, interesting long wavelength solid-state
emitters can be obtained by decorating red emitting dyes with the AIE-active segment, classically
triphenylethene,[12-16] but also triphenylamine which also acts as potent electron-donor group.[17-21]
However, this molecular engineering gives rise to rather big molecular weights and complex structures
requiring sophisticated syntheses. On the other hand, recent works highlighted the interest of simple and
small molecular weight D-π-A push-pull dipolar fluorophores, in which an electron electron-donating
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group D is connected to an electron-withdrawing group A via a π-conjugated bridge, for the design of
efficient solid-state emitters.[22-27],[28-31],[32-39],[40],[41]

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The permanent dipole moment associated with the D-
π
-A structure gives rise to strong dipole-dipole
interactions that can induce specific organization and orientation of molecules in the solid-state and
favors the formation of emissive aggregates. Moreover, since the fluorescence of such dipolar
fluorophores is usually characterized by a large Stokes shift, red and even far-red emission wavelengths
over 700 nm are accessible, providing appropriate combinations of electron-donor and acceptor groups.
Association of electron-deficient 2H-indazoles with electron-rich heteroarenes [42] or of quinoline-
malononitrile electron-withdrawing group with the electron-rich triphenylamino group [43] gives access
to low molecular weight fluorophores with emission wavelengths exceeding 720 nm in the solid-state,
as recently reported. Tuning of the substituents on the core skeleton also greatly influence the molecular
organization in the crystal state and consequently the emission quantum yield in the solid-state, as this
was illustrated in our earlier work on methoxy-substituted push-pull fluorophores bearing 2-
dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofurane (TCF) as electron-acceptor group.[41]
Varying the number and the position of the methoxy groups have a drastic impact on the solid-state
emission modulating the emission wavelength from 580 nm to 730 nm for the reddest shifted dye, while
also influencing the emission efficiency. Similarly, with 2-(3,5,5-trimethylcyclohex-2-en-1-
ylidene)malononitrile (dicyanoisophorone) as electron-accepting group and N,N-dialkylamino group as
electron-donor, emission above 700 nm could be obtained when J-aggregates in the form of inclined
alignment of dipoles are present in the packing resulting in sharpening of the excitation and red-shift of
fluorescence.[40]
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In continuation of our previous works on dipolar solid-state emitters,[40-41] we want to present here a
library of push-pull fluorophores featuring 4-(N,N-diphenylamino)phenyl- (Series 1, Chart 1), 9-ethyl-
9H-carbazolyl- (Series 2) and 4-(9H-carbazol-9-yl)- (Series 3) as electron-donor groups and various
electron-acceptor groups (A - J, Scheme 1), in particular 2(5H)-furanone rings with a weak electron-
withdrawing group at the C2 position (G - J). If some of these acceptor groups such as indanedione (A),
dicyanoisophorone (E) or TCF (F) are quite commonly used in several high efficiency solid-state

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emitters, [32, 38-41, 44-50] other 2(5H)-furanones have rarely been utilized as acceptors entities in dye
design and only within the frame of non-linear optical chromophores design (acceptor group G).[51, 52]
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Chart 1. Structures of fluorophores 1a-1i, 2a-2j and 3b-3i.
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2. Experimental
2.1 General Information
Commercially available materials and reagent grade solvents were used as received. Microwave
syntheses were conducted in 20 mL sealed tube on a Biotage Initiator 2.5 single-mode reactor using
external IR temperature control. The reaction monitoring was performed by analytical thin-layer
chromatography (TLC) on Merck 60 F254 precoated silica gel plate (0.2 mm thickness) with
visualization using a UV lamp. Purification by column chromatography was carried out using 35-70 µm
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silica gel. H and 13C NMR spectra were recorded at ambient temperature on a Bruker Advance 300,

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400 or 500 operating at 300.1, 400.0 or 500.0 MHz for H and 75.0, 101.00 or 125.0 MHz for 13C,
respectively. Chemical shifts are reported as δ values (ppm) with reference to the residual solvent peaks.
For proton, data are reported as follows: chemical shift, multiplicity (s = singlet, d = doublet, t = triplet,
q = quartet, m = multiplet, b = broad), coupling constants in Hz. IR spectra were recorded on a FT/IR-
4200 type A spectrometer. High-resolution mass spectrometry measurements were performed at the
Centre Commun de Spectrométrie de Masse (UCBL, Villeurbanne, France). Melting points were
recorded on a calibrated Koffler bench. Ethyl phenylsulfonylacetate,[53] compounds 1, E and 1e,[40]
3,[54] and F [41] were obtained according to reported procedures. Spectroscopic data for known
compounds 1a,[55] 1b,[56] 1c,[57] 2a,[39] 2b,[56] 2c,[58] 2f [59] matched literature values.
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2.2 Synthetic procedures and characterization data for new compounds
2.2.1
General Protocol 1: Knoevenagel Reaction. Aldehyde (1 equiv.) and acceptor
compound (1 equiv.) were dissolved in acetonitrile (100 mL for 14 mmol.). Piperidine (0.01 equiv.) was
added and solution was stirred at the temperature indicated for the time indicated in each protocol. The
solution was then concentrated under vacuum and the product purified by column chromatography on
silica gel.
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2.2.2
General Protocol 2: Microwave Reaction. Aldehyde (1 equiv.) and acceptor compound
(1 equiv.) were dissolved in a solution of dried acetonitrile (1 mL for 1 mmol) in a microwave tube and
2 drops of piperidine were added. The tube was sealed and the mixture was heated at 110°C for 40
minutes by focused microwave irradiation under controlled temperature. After cooling to room
temperature, the solvents were evaporated under vacuum and the product was purified by column
chromatography on silica gel.
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2.2.3
4,5,5’-trimethyl-2-oxo-2,5-dihydrofuran-3-carbonitrile (G). Sodium (80 mg, 3.3 mmol)
was slowly added at 0°C to dry methanol (4 mL). Once everything was dissolved, 3-hydroxy-3-methyl-
butan-2-one 4 (650 µL, 6.1 mmol) and ethyl cyanoacetate (1.4 mL, 13 mmol) were added at 0°C. After
12 h, the reaction was quenched by the addition of acetic acid (5 mL). The solvents were evaporated

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under reduced pressure. The crude was partitioned between water (25 mL) and CH2Cl2 (25 mL). The
organic phase was dried on Na2SO4, filtered and evaporated. Purification by column chromatography on
silica gel eluting with ethyl acetate / cyclohexane (30/70, v/v) gave G as yellow solid (1.25 g, yield =
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82%): m.p. 54°C; H-NMR (CDCl3, 300 MHz, δ/ppm) 1.50 (s, 6H), 2.28 (s, 3H); 13C-NMR (CDCl3,
101 MHz, δ/ppm) 184.8, 165.4, 110.7, 104.5, 88.3, 24.3, 13.8; IR (ν/cm-1) 3448, 2239, 1764, 1650,
1288, 1080, 910.
2.2.4
Methyl 4,5,5’-trimethyl-2-oxo-2,5-dihydrofuran-3-carboxylate (H). Sodium (80 mg,
3.3 mmol) was added slowly at 0°C to dry methanol (4 mL). After full dissolution, 3-hydroxy-3-methyl-
butan-2-one 4 (650 µL, 6.1 mmol) and methyl malonate (700 µL, 6.1 mmol) were added at 0°C. After
2 h, the reaction was quenched by adding a saturated aqueous NH4Cl solution (10 mL). EtOAc (25 mL)
was then added. The organic phase was separated, dried on Na2SO4, filtered and concentrated under
reduced pressure. Purification by column chromatography on silica gel eluting with EtOAc/petroleum
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ether (30/70, v/v) afforded H (710 mg, yield = 59 %) as white solid; m.p. 65°C; H-NMR (CDCl3,
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300 MHz, δ/ppm) 3.88 (s, 3H), 2.35 (s, 3H), 1.48 (s, 6H); C-NMR (CDCl3, 101 MHz, δ/ppm) 181.2,
167.2, 162.2, 118.0, 85.4, 52.1, 24.3, 13.0; IR (ν/cm-1) 1760, 1711, 1350, 1280, 1191, 1174, 1043, 969,
808.
2.2.5
3-(benzo[d]thiazol-2-yl)-4,5,5-trimethylfuran-2(5H)-one (I). G (906 mg, 6 mmol), 2-
hydroxythiophenol (640 µL, 6 mmol) and 85% aqueous phosphoric acid (3 g) were heated at 120°C for
14 h. After cooling down to room temperature, water (50 mL) was added. The mixture was carefully
neutralized by slow addition of saturated aqueous K2CO3 (50 mL). The solution was extracted with
dichloromethane three times. The combined organic layers were washed with water, dried over Na2SO4,
filtered and evaporated to dryness to give I, used without further purification. Brown solid (1.41 g, yield
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= 91 %); m.p. 158-160°C; H-NMR (CDCl3, 300 MHz, δ/ppm) 8.07 (d, J = 8.2 Hz, 1H), 7.94 (d, J =
8.2 Hz, 1H), 7.53 (t, J = 8.2 Hz, 1H), 7.43 (t, J = 8.2 Hz, 1H), 2.68 (s, 3H), 1.59 (s, 6H); 13C-NMR
(CDCl3, 101 MHz, δ/ppm) 172.3, 170.3, 157.9, 153.0, 135.1, 126.3, 125.6, 123.3, 121.8, 119.0, 87.0,
24.7, 13.6; IR (ν/cm-1) 2173, 1644, 1497, 1055, 970, 958, 764.

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2.2.6
4,5,5’-trimethyl-3-(phenylsulfonyl)furan-2(5H)-one (J). Sodium (70 mg, 3.04 mmol)
was slowly added at 0°C to dry methanol (5 mL). After complete dissolution, 3-hydroxy-3-methyl-
butan-2-one 4 (1.05 mL, 10 mmol.) and ethyl phenylsulfonylacetate (2.51 g, 11 mmol) were added at
0°C. The mixture was then heated at 50°C overnight. After cooling to room temperature, the solvent
was removed under reduced atmosphere to give an oily residue. Et2O was added to precipitate the
product. The solid was filtered, washed with Et2O and dried. Recrystallization in a mixture Et2O/EtOAc
(40 mL / 4 mL) gave compound J as white solid (1.5 g, 56%); m.p. 172°C; 1H-NMR (CDCl3, 300 MHz,
δ/ppm) 8.08 (d, J = 7.5 Hz, 2H), 7.66 (t, J = 7.3 Hz, 1H), 7.56 (t, J = 7.2 Hz, 2H), 2.51 (s, 3H), 1.47 (s,
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6H). C-NMR (CDCl3, 101 MHz, δ/ppm) 179.1, 164.7, 139.4, 134.4, 129.3, 128.8, 126.9, 86.7, 24.3,
12.6. IR (ν/cm-1) 1746, 1320, 1311, 1266, 1149, 1084, 1029, 719, 685.
2.2.7
2-(4-(diphenylamino)benzylidene)-1H-indene-1,3(2H)-dione (1a). From 1 (400 mg,
1.45 mmol.) and A (255 mg, 1.75 mmol.) following general protocol 1 (40°C, 18 h). Purification by
chromatography (Petroleum ether, EtOAc: 9/1 v/v) afforded the title compound 1a. Red solid (230 mg,
1
yield = 33%); m.p. 214°C; H-NMR (CD2Cl2, 400 MHz, δ/ppm) 8.41 (d, J = 8.8 Hz, 2H), 8.06 – 7.85
(m, 2H), 7.76 (dd, J = 10.7, 5.3 Hz, 3H), 7.39 (t, J = 7.7 Hz, 4H), 7.23 (d, J = 6.2 Hz, 6H), 6.99 (d, J =
8.8 Hz, 2H); 13C-NMR (CD2Cl2, 101 MHz, δ/ppm) 191.3 (CO), 153.2, 146.5 (CH), 146.2, 142. 9, 140.5,
137.2 (2 x CH), 135.3 (CH), 135.12 (CH), 130.3 (4 x CH), 127.2 (4 x CH), 126.1 (2 x CH), 123.2 (CH),
123.1 (CH), 119.1 (2 x CH); IR (ν/cm-1) 3062, 1680 (νCO), 1570/1542/1487, 1265, 1154; HRMS (ESI+)
calcd for C28H20NO2 [M+H]+: 402.1489, found: 402.1482; UV-Vis (CH2Cl2) λmax = 485 nm (ε =
37 800 L.mol-1.cm-1).
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2.2.8
(Z)-3-(4-(diphenylamino)phenyl)-2-(4-nitrophenyl)acrylonitrile (1b). From
1
(350 mg, 1.25 mmol.) and B (250 mg, 1.5 mmol.) following general protocol 1 (45°C, 4 h). Purification
by chromatography (CH2Cl2) afforded the title compound 1b. Red solid (340 mg, yield = 33%); m.p.
145°C; 1H-NMR (CD2Cl2, 500 MHz, δ/ppm) 8.27 (d, J = 8.8 Hz, 2H), 7.83 (dd, J = 12.6, 8.9 Hz, 4H),
7.60 (s, 1H), 7.36 (t, J = 7.8 Hz, 4H), 7.19 (d, J = 7.9 Hz, 6H), 7.03 (d, J = 8.8 Hz, 2H); 13C NMR (125

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MHz, CD2Cl2, δ/ppm) 151.8, 148.1, 147.0, 145.5, 142.3, 132.2 (2 x CH), 130.4 (4 x CH), 126.9 (4 x
CH), 126.9 (2 x CH), 126.0, 125.7 (2 x CH), 125.0 (2 x CH), 120.6 (2 x CH), 118.8, 105.5 (CN); IR
(ν/cm-1) 3060, 2208 (νCN), 1572/1490/1508, 1338, 1198, 700; HRMS (ESI+) calcd for C27H20N3O2
[M+H]+: 418.1550, found: 418.1543; UV-Vis (CH2Cl2) λmax = 456 nm (ε = 28 700 L.mol-1.cm-1).
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2.2.9
(Z)-3-(4-(diphenylamino)phenyl)-2-(pyridin-4-yl)acrylonitrile (1c). From 1 (100 mg,
0.4 mmol.) and C (70 mg, 0.45 mmol.) following general protocol 1 (40°C, 4 h). Purification by
chromatography (CH2Cl2/Et3N: 95/5 then 92/8 v/v) afforded the title compound 1c. Orange solid
(90 mg, yield = 60%); m.p. 182°C. 1H-NMR (CD2Cl2, 500 MHz, δ/ppm) 8.62 (d, J = 4.8 Hz, 2H), 7.83
(d, J = 8.8 Hz, 4H), 7.64 (s, 1H), 7.56 – 7.46 (m, 2H), 7.35 (t, J = 7.8 Hz, 4H), 7.18 (t, J = 8.0 Hz, 6H),
7.03 (d, J = 8.8 Hz, 2H); 13C-NMR (CD2Cl2
125 MHz, δ/ppm) 151.1, 150.6 (2 x CH), 146.4, 144.4,
,
142.5, 131.5 (2 x CH), 129.8 (4 x CH), 126.3 (4 x CH), 125.3, 125.0 (2 x CH), 120.0 (2 x CH), 119.6 (2
x CH), 117.9, 104.6 (CN); IR (ν/cm-1) 3057, 2924, 2206 (νCN), 1577/1557/1487, 1176, 756. HRMS
(ESI+) calcd for C26H20N3 [M+H]+: 374.1652, found: 374.1656; UV-Vis (CH2Cl2) λmax = 427 nm (ε =
29 700 L.mol-1.cm-1).
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2.2.10
(E)-2-(benzo[d]thiazol-2-yl)-3-(4-(diphenylamino)phenyl)acrylonitrile (1d). From 1
(700 mg, 2.5 mmol.) and D (520 mg, 3 mmol.) following general protocol 1 (40°C, 4 h). Purification by
chromatography (eluting with CH2Cl2) afforded the title compound 1d. Red solid (840 mg, yield =
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79%); m.p. 173°C; H-NMR (CD2Cl2, 500 MHz, δ/ppm) 8.05 (s, 1H), 8.01 (d, J = 5.0 Hz, 1H), 7.92 –
7.89 (m, 3H), 7.52 (dd, J = 11.2, 4.0 Hz, 1H), 7.41 (dd, J = 11.2, 4.0 Hz, 1H), 7.39 – 7.30 (m, 4H), 7.26
– 7.14 (m, 6H), 7.02 (d, J = 8.9 Hz, 2H); 13C-NMR (CD2Cl2, 125 MHz, δ/ppm) 164.9, 154.5, 152.4,
147.2 (CH), 146.7 (CH), 135.4, 132.9 (2 x CH), 130.5 (4 x CH), 127.5 (CH), 127.1 (4 x CH), 126.3
(CH), 126.0 (2 x CH), 125.2, 123.8 (CH), 122.4 (CH), 120.2 (2 x CH), 118.0, 101.8 (CN); IR (ν/cm-1)
3056, 2210 (νCN), 1570/1487/1506, 1430, 1174, 987; HRMS (ESI+) calcd for C28H20N3S [M+H]+:
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430.1372, found: 430.1357; UV-Vis (CH2Cl2) λmax = 454 nm (ε = 31 200 L.mol-1.cm-1).

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2.2.11
(E)-2-[3-cyano-4-(4-(diphenylamino)styryl)-5,5-dimethylfuran-2(5H)-
ylidene]malononitrile (1f). From 1 (546 mg, 2 mmol.) and TCF F (318 mg, 1.6 mmol.) following a
slightly modified general protocol 1. Toluene (2 mL) was added in the initial mixture. The mixture was
heated at 80°C for 24 h, then cooled to room temperature. The mixture was concentrated under vacuum
and Et2O (10 mL) was added to precipitate the compound. It was then filtered, washed with Et2O (2x10
mL) and with ethanol (2x10 mL), and dried. 1f was obtained as green solid (380 mg, yield = 53%); m.p.
> 250°C (dec); 1H NMR (500 MHz, CDCl3, δ/ppm) 7.58 (d, J = 16.1 Hz, 1H), 7.46 (d, J = 8.4 Hz, 2H),
7.36 (t, J = 7.1 Hz, 4H), 7.20 (dd, J = 18.9, 7.4 Hz, 6H), 6.98 (d, J = 8.4 Hz, 2H), 6.82 (d, J = 16.1 Hz,
1H), 1.76 (s, 6H); 13C NMR (125 MHz, CDCl3, δ/ppm) 176.2, 174.3, 152.9, 147.6 (CH), 146.0, 131.5 (2
x CH), 130.2 (4 x CH), 126.7 (4 x CH), 126.3, 126.0 (2 x CH), 120.3 (2 x CH), 112.6, 111.8, 111.6
(CH), 111.3, 97.5 (2 x CN), 97.1 (CN), 56.6, 27.0 (2 x CH3); IR (ν/cm-1) 2223 (νCN), 1742, 1560, 1545,
1528, 1488, 1330, 1283, 1266, 1168, 758, 698; HRMS (ESI+) calcd for C30H23N4O [M+H]+: 455.1866,
found: 455.1857; UV-Vis (CH2Cl2) λmax = 565 nm (ε = 42 000 L.mol-1.cm-1).
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2.2.12
3-cyano-4-[2-[4-(diphenylamino)phenyl]ethenyl]-5,5-dimethyl-2-butenolide
(1g).
From 1 (273 mg, 1 mmol) and G (151 mg, 1 mmol) in acetonitrile (2 mL) and toluene (0.5 mL) using
general protocol 2. Purification by chromatography (EtOAc/Petroleum ether: 30/70) afforded the title
compound 1g. Red solid (340 mg, yield = 83%); m.p. 171°C; 1H-NMR (CD2Cl2, 500 MHz, δ/ppm) 7.65
(d, J = 16.3 Hz, 1H), 7.49 (d, J = 8.8 Hz, 2H), 7.35 (t, J = 7.9 Hz, 4H), 7.17 (t, J = 7.8 Hz, 6H), 6.99 (d,
J = 8.8 Hz, 2H), 6.75 (d, J = 16.3 Hz, 1H), 1.65 (s, 6H); 13C-NMR (CD2Cl2, 125 MHz, δ/ppm) 177.1
(CO), 167.2, 151.9, 146.8, 146.0 (CH), 130.6 (2 x CH), 130.2 (4 x CH), 127.0, 126.6 (4 x CH), 125.5 (2
x CH), 120.8 (2 x CH), 113.3, 112.3 (CH), 96.7 (CN), 87.4, 26.4 (2 x CH3); IR (ν/cm-1) 2223 (νCN),
221
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1735 (νCO), 1556, 1506, 1486, 1279, 1262, 1175, 697; HRMS (ESI+) calcd for C27H22N2O2Na [M+Na]+:
429.7573, found: 429.1570; UV-Vis (CH2Cl2) λmax = 484 nm (ε = 38 400 L.mol-1.cm-1).
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2.2.13
3-methyl ester-4-[2-[4-(diphenylamino)phenyl]ethenyl]-5,5-dimethyl-2-butenolide
(1h). From 1 (273 mg, 1 mmol.) and H (200 mg, 1 mmol.) following general protocol 1 (80°C, 24 h).

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Purification by chromatography (EtOAc/Pentane: 20/80) afforded the title compound 1h. Yellow solid
1
(350 mg, yield = 74%); m.p. 174 °C; H-NMR (CDCl3, 500 MHz, δ/ppm) 7.75 (d, J = 16.9 Hz, 1H),
7.46 (d, J = 8.7 Hz, 2H), 7.36 – 7.26 (m, 4H), 7.18 (d, J = 16.9 Hz, 1H), 7.15 – 7.11 (m, 6H), 7.01 (d, J
= 8.7 Hz, 2H), 3.88 (s, 3H), 1.71 (s, 6H); 13C-NMR (CDCl2, 125 MHz, δ/ppm) 173.6, 167.7, 163.5,
151.0, 147.2, 143.3 (CH), 130.1 (4 x CH), 130.0, 128.5, 126.3 (4 x CH), 125.0 (2 x CH), 121.6 (2 x
CH), 115.5 (CH), 114.9, 84.5, 52.5 (CH3), 27.6 (2 x CH3); IR (ν/cm-1) 1736 (νCO), 1561, 1486, 1283,
1265, 1219, 1169, 1050, 760, 699; HRMS (ESI+) calcd for C28H25NO4Na [M+Na]+: 462.1676, found:
462.1656; UV-Vis (CH2Cl2) λmax = 483 nm (ε = 31 300 L.mol-1.cm-1).
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2.2.14
3-(2-benzothiazolyl)-4-[2-[4-(diphenylamino)phenyl]ethenyl]-5,5-dimethyl-2-
butenolide (1i). From 1 (273 mg, 1 mmol.) and I (259 mg, 1 mmol.) in acetonitrile (3 mL) and toluene
(0.5 mL) according to general protocol 2. The microwave irradiations were applied at 100°C for 3 h.
Purification by chromatography (EtOAc/Cyclohexane: 30/70) afforded the title compound 1i. Red solid
1
(410 mg, yield = 80%); m.p. 165-170°C; H-NMR (CD2Cl2, 500 MHz, δ/ppm) 8.83 (d, J = 17.0 Hz,
1H), 8.12 (d, J = 8.1 Hz, 1H), 7.99 (d, J = 7.8 Hz, 1H), 7.59 (d, J = 8.5 Hz, 2H), 7.51 (dd, J = 7.5 Hz,
1H), 7.43 (dd, J = 7.5 Hz, 1H), 7.35 – 7.27 (m, 5H), 7.20 – 7.10 (m, 6H), 7.07 (d, J = 8.1 Hz, 2H), 1.83
(s, 6H); 13C-NMR (CD2Cl2
125 MHz, δ/ppm) 170.7, 165.7, 159.2, 153.7, 150.7, 147.3, 142.5 (CH),
,
135.5, 130.1 (4 x CH), 130.0 (2 x CH), 129.3, 126.7 (CH), 126.2 (4 x CH), 125.9 (CH), 124.9 (2 x CH),
123.6 (CH), 122.1 (CH), 121.8 (2 x CH), 117.5 (CH), 116.2, 85.8, 27.8 (2 x CH3); IR (ν/cm-1) 1735,
1583, 1562, 1486, 1265, 1171, 1141, 1024, 975, 761, 753, 696; HRMS (ESI+) calcd for C33H27N2O2S
[M+H]+: 515.1788, found: 515.1776; UV-Vis (CH2Cl2) λmax = 455 nm (ε = 34 900 L.mol-1.cm-1).
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2.2.15
2-((9-ethyl-9H-carbazol-3-yl)methylene)-1H-indene-1,3(2H)-dione (2a). From 2 (340
mg, 1.5 mmol.) and A (175 mg, 1.2 mmol.), following general protocol 1 (45°C, 26 h). Purification by
chromatography (petroleum ether/EtOAc: 3/1 v/v) afforded the title compound 2a. Orange solid (330
1
mg, yield = 78%); m.p. 230°C; H-NMR (CD2Cl2, 500 MHz, δ/ppm) 9.46 (s, 1H), 8.72 (d, J = 8.7 Hz,
1H), 8.24 (d, J = 7.7 Hz, 1H), 8.08 (s, 1H), 8.01 (dd, J = 5.4, 2.7 Hz, 1H), 7.96 (dd, J = 5.2, 2.9 Hz, 1H),

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7.88 – 7.75 (m, 2H), 7.60 – 7.49 (m, 3H), 7.35 (t, J = 7.4 Hz, 1H), 4.43 (q, J = 7.3 Hz, 2H), 1.48 (t, J =
13
7.3 Hz, 3H); C-NMR (CD2Cl2
,
125 MHz, δ/ppm) 191.4 (CO), 190.2 (CO), 148.8 (CH), 143.8, 143.0,
141.3, 140.5, 135.4 (CH), 135.2 (CH), 133.7 (CH), 129.0 (CH), 127.3 (CH), 126.3 (CH), 125.4 (CH),
124.1 (CH), 123.8 (CH), 123.3 (CH), 123.2 (CH), 121.4 (CH), 121.1 (CH), 110.0 (CH), 109.4 (CH),
38.6 (CH2), 14.2 (CH3); IR (ν/cm-1) 3059, 1665 (νCO), 1571/1553/1471, 1129; HRMS (ESI+) calcd for
C24H18NO2 [M+H]+: 352.1332, found: 352.1328; UV-Vis (CH2Cl2) λmax = 453 nm (ε = 44 800 L.mol-
1.cm-1).
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2.2.16
(Z)-3-(9-ethyl-9H-carbazol-3-yl)-2-(4-nitrophenyl)acrylonitrile (2b). From 2 (450 mg,
2 mmol.) and B (400 mg, 2.5 mmol.) following general protocol 1 (45°C, 18 h). Purification by
chromatography (CH2Cl2) afforded the title compound 2b. Orange solid (240 mg, yield = 33%); m.p.
244°C; 1H-NMR (DMSO-d6, 300 MHz, δ/ppm) 8.82 (d, J = 1.4 Hz, 1H), 8.43 (s, 1H), 8.34 (d, J = 8.9
Hz, 2H), 8.25 (dd, J = 8.7, 1.7 Hz, 1H), 8.14 (d, J = 7.7 Hz, 1H), 8.04 (d, J = 8.9 Hz, 2H), 7.82 (d, J =
8.7 Hz, 1H), 7.70 (d, J = 8.2 Hz, 1H), 7.54 (t, J = 7.7 Hz, 1H), 7.31 (t, J = 7.5 Hz, 1H), 4.51 (q, J = 7.1
13
Hz, 2H), 1.35 (t, J = 7.1 Hz, 3H); C-NMR (DMSO-d6, 101 MHz, δ/ppm) 147.6 (CH), 146.8, 141.4,
141.1, 140.3, 127.2 (CH), 126.8 (CH), 126.4 (CH), 124.5 (2 x CH), 124.2, 123.6 (2 x CH), 122.5, 122.1,
120.4 (CH), 120.1 (CH), 118.5, 110.0 (CH), 103.8 (CN), 37.4 (CH2), 13.8 (CH3); IR (ν/cm-1) 2208
(νCN), 1576/1515/1472, 1334, 1231, 1159; HRMS (ESI+) calcd for C23H17N3O2Na [M+Na]+: 390.1213,
found: 390.1207; UV-Vis (CH2Cl2) λmax = 405 nm (ε = 21 300 L.mol-1.cm-1).
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2.2.17
(Z)-3-(9-ethyl-9H-carbazol-3-yl)-2-(pyridine-4-yl)acrylonitrile (2c). From 2 (300 mg,
1.35 mmol.) and C (250 mg, 1.5 mmol.) following general protocol 2 (60°C, 48 h). Purification by
chromatography (petroleum ether, EtOAc: 6/1 v/v) afforded the title compound. Orange solid (130 mg,
1
yield = 30%); m.p. 216°C; H-NMR (DMSO-d6, 300 MHz, δ/ppm) 8.84-8.64 (m, 3H), 8.45 (s, 1H),
8.24 (dd, J = 8.8, 1.6 Hz, 1H), 8.14 (d, J = 7.7 Hz, 1H), 7.85 – 7.66 (m, 4H), 7.59 – 7.49 (m, 1H), 7.30
13
(t, J = 7.4 Hz, 1H), 4.49 (q, J = 7.1 Hz, 2H), 1.33 (t, J = 7.1 Hz, 3H), C-NMR (DMSO-d6, 75 MHz,
δ/ppm) 150.4, 147.0, 141.8, 141.3, 140.2, 127.1, 126.7, 124.0, 123.5, 122.4, 122.0, 120.3, 120.001,

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119.4, 118.0, 109.9, 109.8, 103.3, 37.3, 13.7; IR (ν/cm-1) 2926, 2214 (νCN), 1628, 1573/1492, 1234;
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HRMS (ESI+) calcd for C22H18N3 [M+H]+: 324.1495, found: 324.1483; UV-Vis (CH2Cl2) λmax
389 nm (ε = 25 000 L.mol-1.cm-1).
=
2.2.18
(E)-2-(benzo[d]thiazol-2-yl)-3-(9-ethyl-9H-carbazol-3-yl)acrylonitrile (2d). From 2
(400 mg, 1.8 mmol.) and D (375 mg, 2.5 mmol.) following general protocol 2 (40°C, 18 h). Purification
by chromatography (CH2Cl2) afforded the title compound 2d. Orange solid (680 mg, yield = 57%). m.p.
230°C; 1H-NMR (CD2Cl2, 500 MHz, δ/ppm) 8.80 (s, 1H), 8.37 (s, 1H), 8.28 (dd, J = 8.7, 1.5 Hz, 1H),
8.19 (d, J = 7.8 Hz, 1H), 8.06 (d, J = 8.1 Hz, 1H), 7.95 (d, J = 8.0 Hz, 1H), 7.62 – 7.48 (m, 4H), 7.44 (t,
13
J = 7.6 Hz, 1H), 7.34 (t, J = 7.0 Hz, 1H), 4.44 (q, J = 7.3 Hz, 2H), 1.48 (t, J = 7.3 Hz, 3H); C NMR
(125 MHz, CH2Cl2, δ/ppm) 164.8, 154.3, 148.8 (CH), 142.7, 141.2, 135.2, 128.7 (CH), 127.2 (2 x CH),
126.1 (CH), 124.7 (CH), 124.0, 123.6 (CH), 123.3, 122.1 (CH), 121.3 (CH), 120.8 (CH), 118.0, 109.8
(2 x CH), 101.8, 38.5 (CH2), 14.2 (CH3); IR (ν/cm-1) 2361, 1576/1559/1469, 1233, 1128; HRMS (ESI+)
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calcd for C24H18N3S [M+H]+: 380.1216, found: 380.1207; UV-Vis (CH2Cl2) λmax = 417 nm (ε =
20 300 L.mol-1.cm-1).
2.2.19
(E)-2-(3-cyano-4-(2-(9-ethyl-9H-carbazol-3-yl)vinyl)-5,5’-dimethylfuran-2(5H)-
ylidene)malononitrile (2f). From 2 (340 mg, 1.5 mmol.) and F (380 mg, 1.9 mmol.) following general
protocol 1 (45°C, 48 h). Purification by chromatography (CH2Cl2/pentane: 1/1 then 2/1 v/v) afforded
1
the title compound 2f. Red solid (180 mg, yield = 30%); m.p. 230°C; H-NMR (DMSO-d6, 400 MHz,
δ/ppm) 8.79 (d, J = 1.3 Hz, 1H), 8.27 (d, J = 7.7 Hz, 1H), 8.18 (d, J = 16.2 Hz, 1H), 8.07 (dd, J = 8.8,
1.5 Hz, 1H), 7.76 (d, J = 8.7 Hz, 1H), 7.70 (d, J = 8.2 Hz, 1H), 7.60 – 7.48 (m, 1H), 7.31 (dd, J = 11.1,
3.8 Hz, 1H), 7.26 (d, J = 16.2 Hz, 1H), 4.50 (q, J = 7.1 Hz, 2H), 1.83 (s, 6H), 1.34 (t, J = 7.1 Hz, 3H);
13C NMR (DMSO-d6, 101 MHz, δ/ppm) 177.4, 175.8, 149.9 (CH), 142.4, 140.3, 127.9 (CH), 126.9
(CH), 125.6, 123.9 (CH), 123.1, 122.3, 121.0 (CH), 120.3 (CH), 113.1, 112.3, 111.9 (CH), 111.5, 110.2
(CH), 110.1 (CH), 99.0, 96.0, 53.0, 37.4 (CH2), 25.4 (2 x CH3), 13.9 (CH3); IR (ν/cm-1) 2219 (νCN),
1542/1508/1490, 1394, 1106; HRMS (ESI+) calcd for C26H20N4ONa [M+Na]+: 427.1529, found:

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427.1515 (calcd.); UV-Vis (CH2Cl2) λmax = 510 nm (ε = 24 000 L.mol-1.cm-1).
2.2.20
(E)-methyl-4-(2-(9-ethyl-9H-carbazol-3-yl)vinyl)-5,5’-dimethyl-2-oxo-2,5-
dihydrofuran-3-carboxylate (2h). From 2 (470 mg, 2.1 mmol.) and H (330 mg, 1.8 mmol.) following
general protocol 1 (50°C, 48 h). Purification by chromatography (Petroleum ether, EtOAc: 6/1 v/v)
1
afforded the title compound 2h. Orange solid (450 mg, yield = 65%); m.p. 218°C; H-NMR (CD2Cl2,
400 MHz, δ/ppm) 8.35 (s, 1H), 8.16 (d, J = 7.7 Hz, 1H), 7.97 (d, J = 16.9 Hz, 1H), 7.81 (d, J = 8.6 Hz,
1H), 7.59 – 7.40 (m, 4H), 7.30 (t, J = 7.3 Hz, 1H), 4.40 (q, J = 7.1 Hz, 2H), 3.94 (s, 3H), 1.79 (s, 6H),
1.45 (t, J = 7.2 Hz, 3H); 13C-NMR (CD2Cl2, 101 MHz, δ/ppm) 174.1, 167.95, 163.8, 145.4 (CH), 142.3,
141.2, 127.2 (CH), 126.4 (CH), 124.1, 123.4, 122.3 (CH), 121.2 (CH), 120.5 (CH), 115.3 (CH), 114.3,
109.8 (CH), 84.7, 52.7 (CH), 38.6, 27.8 (2 x CH3), 14.3 (CH3); IR (ν/cm-1) 2364, 1759,
1572/1542/1490, 1333, 1213, 1123; HRMS (ESI+) calcd for C24H23NO4Na [M+Na] +: 412.1519, found:
412.1511; UV-vis (CH2Cl2) λmax = 413 nm (ε = 22 590 L.mol-1.cm-1).
2.2.21
(E)-3-(benzo[d]thiazol-2-yl)-4-(2-(9-ethyl-9H-carbazol-3-yl)vinyl)-5,5’-
dimethylfuran-2(5H)-one (2i). From 2 (300 mg, 1.3 mmol.) and I (420 mg, 1.6 mmol.) following
general protocol 1 (70°C, 48 h). Purification by chromatography (Petroleum ether, EtOAc: 6/1 v/v)
afforded the title compound 2i. Orange solid (240 mg, yield = 78%); m.p. 223°C; 1H NMR (500 MHz,
CD2Cl2, δ/ppm) .89 (d, J = 16.9 Hz, 1H), 8.35 (d, J = 1.1 Hz, 1H), 8.14 (d, J = 8.1 Hz, 1H), 8.08 (d, J =
7.7 Hz, 1H), 8.02 – 7.85 (m, 1H), 7.81 (dd, J = 8.6, 1.5 Hz, 1H), 7.58 – 7.30 (m, 6H), 7.21 (dd, J = 10.9,
3.8 Hz, 1H), 4.31 (q, J = 7.3 Hz, 2H), 1.78 (s, 6H), 1.36 (t, J = 7.3 Hz, 3H); 13C NMR (125 MHz,
CD2Cl2, δ/ppm) 170.7, 165.9, 159.2, 153.6, 144.3, 141.9, 141.0, 135.5, 127.4, 126.9, 126.6, 126.3,
125.8, 125.8, 123.9, 123.5, 123.2, 122.1, 122.0, 121.8, 120.9, 120.2, 117.0, 115.9, 109.8, 109.6, 87.3,
85.7, 38.3, 27.7, 24.7, 14.0, 13.7; IR (ν/cm-1) 2364, 1748, 1559/1471/1457, 1233, 1122; HRMS (ESI+)
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calcd for C29H24N2O2SNa [M+Na]+: 487.1451, found 487.1436; UV-Vis (CH2Cl2) λmax = 452 nm
(ε = 22 600 L.mol-1.cm-1).
2.2.22
(E)-4-(2-(9-ethyl-9H-carbazol-3-yl)vinyl)-5,5’-dimethyl-3-(phenylsulfonyl)furan-

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2(5H)-one (2j). From 2 (320 mg, 1.4 mmol.) and J (320 mg, 1.2 mmol.) following general protocol 1
(50°C, 48 h). Purification by chromatography (petroleum ether, EtOAc: 6/1 v/v) afforded the title
1
compound 2j. Orange solid (165 mg, yield = 29%); m.p. 224°C; H-NMR (CD2Cl2, 500 MHz, δ/ppm)
8.4 (s, 1H), 8.35 (d, J=16.8 Hz, 1H), 8.18 (d, J=7.6 Hz, 1H), 8.10 (d, J=7.6 Hz, 2H), 7.91 (d, J=8.5Hz,
1H), 7.67 (t, J=7.3 Hz, 1H), 7.60-7.52 (m, 6H), 7.32 (t, J=7.3 Hz, 1H), 4.43 (q, J=7.2 Hz, 2H), 1.77 (s,
6H), 1.48 (t, J=7.2 Hz, 3H); 13C NMR (125 MHz, CD2Cl2, δ/ppm) 172.2, 165.6, 147.3, 142.6, 141.2,
141.0, 134.5, 129.6, 128.9, 127.2, 126.6, 124.2, 123.3, 123.0, 121.7, 121.2, 120.6, 113.2, 110.1, 109.8,
85.7, 38.6, 27.8, 14.2; IR (ν/cm-1) 1748, 1583/1529/1472, 1330, 1234, 1148; HRMS (ESI+) calcd for
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C28H25NO4SNa [M+Na]+: 494.1397, found 494.1378; UV-Vis (CH2Cl2) λmax = 439 nm
(ε = 26 100 L.mol-1.cm-1).
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2.2.23
(Z)-3-(4-(9H-carbazol-9-yl)phenyl)-2-(4-nitrophenyl)acrylonitrile (3b). From 3 (500
mg, 1.85 mmol.) and B (450 mg, 2.78 mmol.) following general protocol 1 (40°C, 18 h). Purification by
chromatography (Petroleum ether/EtOAc: 6/1 v/v) afforded the title compound 3b. Orange solid (430
mg, yield = 56%); m.p. 223°C; 1H-NMR (CD2Cl2, 500 MHz, δ/ppm) 8.34 (d, J = 8.0 Hz, 2H), 8.23 (d, J
= 7.8 Hz, 2H), 8.17 (d, J = 7.7 Hz, 2H), 7.93 (d, J = 7.9 Hz, 2H), 7.85 – 7.76 (m, 3H), 7.55 (d, J = 8.2
Hz, 2H), 7.46 (t, J = 7.6 Hz, 2H), 7.33 (t, J = 7.4 Hz, 2H); 13C-NMR (CD2Cl2, 125 MHz, δ/ppm) 144.8,
140.8, 131.9, 127.4, 126.8, 124.9, 124.3, 121.2, 121.0, 117.7, 110.4; IR (ν/cm-1) 2219, 1588/1511/1448,
1220, 1170; HRMS (EI) calcd for C27H17N3O2 [M]+ ñ: 416.1315, found: 415.1317; UV-Vis (CH2Cl2)
λmax = 404 nm (ε = 21 110 L.mol-1.cm-1).
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2.2.24
(E)-2-(4-(4-(9H-carbazol-9-yl)styryl)-3-cyano-5,5’-dimethylfuran-2(5H)-
ylidene)malononitrile (3f). From 3 (270 mg, 1 mmol.) and F (240 mg, 1,2 mmol.) following general
protocol 1 (50°C, 18 h). Purification by chromatography (Pentane/EtOAc: 70/30 v/v) afforded the title
1
compound 3f. Black solid (175 mg, yield = 39%); m.p. > 260°C; H-NMR (DMSO-d6, 500 MHz,
δ/ppm) 8.28 (d, J = 7.8 Hz, 2H), 8.22 (d, J = 8.5 Hz, 2H), 8.07 (d, J = 16.5 Hz, 1H), 7.83 (d, J = 8.6 Hz,
2H), 7.49 (ddd, J = 13.3, 9.4, 4.7 Hz, 4H), 7.39 – 7.27 (m, 3H), 1.86 (s, 6H); 13C-NMR (DMSO-d6, 125

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MHz, δ/ppm) 176.9, 174.9, 146.0 (CH), 139.9, 139.4 (CH), 133.0, 131.1 (CH), 126.6 (CH), 126.3 (CH),
123.0 (CH), 120.5, 115.7, 112.5, 111.7, 110.7, 109.7 (CH), 99.6 (CN), 99.3 (2 x CN), 54.4, 25.0 (CH3);
IR (ν/cm-1) 2989, 2223, 2202, 1567, 1553, 1165, 745; HRMS (ESI+) calcd for C30H20N4ONa [M+Na]+:
475.1529, found: 475.1516; UV-Vis (CH2Cl2) λmax = 481 nm (ε = 29 700 L.mol-1.cm-1).
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2.2.25
(E)-4-(4-(9H-carbazol-9-yl)styryl)-5,5’-dimethyl-2-oxo-2,5
dihydrofuran-3-
carbonitrile (3g). From 3 (270 mg, 1 mmol.) and G (150 mg, 1 mmol.) following general protocol 1
(70°C, 4 h. Purification by chromatography (EtOAc/Pentane: 30/70) afforded the title compound 3g.
Yellow solid (290 mg, yield = 72%); m.p. 203°C; 1H-NMR (CDCl3, 500 MHz, δ/ppm) 8.16 (d, J = 7.7
Hz, 2H), 7.88 (d, J = 8.4 Hz, 2H), 7.83 (d, J = 16.5 Hz, 1H), 7.73 (d, J = 8.4 Hz, 2H), 7.54 – 7.41 (m,
4H), 7.33 (t, J = 7.4 Hz, 2H), 6.98 (d, J = 16.4 Hz, 1H), 1.74 (s, 6H); 13C-NMR (CDCl3, 125 MHz,
δ/ppm) 176.0, 166.0, 144.5 (CH), 141.1, 140.3, 132.7, 130.2 (2 x CH), 127.4 (2 x CH), 126.4 (2 x CH),
124.0, 120.9 (2 x CH), 120.7 (2 x CH), 115.4 (CH), 112.2, 109.9 (2 x CH), 99.4, 87.0, 26.1 (2 x CH3);
IR (ν/cm-1) 2233 (νCN), 1763, 1585, 1516, 1449, 1334, 1276, 1231, 1219, 1172, 1069, 750, 723; HRMS
(ESI+) calcd for C27H20N2O2Na [M+Na]+: 427.1417, found: 427.1413; UV-Vis (CH2Cl2) λmax = 421 nm
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(ε = 21 070 L.mol-1.cm-1).
2.2.26
(E)-methyl-4-(4-(9H-carbazol-9-yl)styryl)-5,5’-dimethyl-2-oxo-2,5-dihydrofuran-3-
carboxylate (3h). From 3 (270 mg, 1 mmol.) and H (200 mg, 1 mmol.) following general protocol 1
(80°C, 12 h). Purification by chromatography (Cyclohexane/EtOAc: 80/20 v/v) afforded the title
compound 3h. Yellow solid (330 mg, yield = 78 %); m.p. 174°C; 1H-NMR (CD2Cl2, 500 MHz, δ/ppm)
8.16 (d, J = 7.7 Hz, 2H), 7.96 (d, J = 17.0 Hz, 1H), 7.88 (d, J = 8.3 Hz, 2H), 7.70 (d, J = 8.3 Hz, 2H),
13
7.50 (d, J = 8.2 Hz, 2H), 7.45 (t, J = 7.5 Hz, 2H), 7.40 – 7.29 (m, 3H), 3.94 (s, 3H), 1.78 (s, 6H); C-
NMR (CD2Cl2, 125 MHz, δ/ppm) 158.2, 152.9, 148.7, 127.6 (CH), 126.5, 125.8, 120.1, 115.6 (2 x CH),
113.2 (2 x CH), 112.2 (2 x CH), 106.5 (2 x CH), 106.4 (2 x CH), 104.3 (CH), 102.9, 95.9 (2 x CH),
86.0, 70.3, 38.3 (CH3), 12.9 (2 x CH3); IR (ν/cm-1) 1748 (νCO), 1587, 1515, 1450, 1230, 1215, 1049,
746, 723; HRMS (ESI+) calcd for C28H23NO4Na [M+Na]+: 460.1519, found: 460.1506; UV-Vis

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(CH2Cl2) λmax = 397 nm (ε = 23 200 L.mol-1.cm-1).
2.2.27 (E)-4-(4-(9H-carbazol-9-yl)styryl)-3-(benzo[d]thiazol-2-yl)-5, 5’- dimethylfuran-
2(5H)-one (3i). From 3 (270 mg, 1 mmol.) and I (260 mg, 1 mmol.) following general protocol 1
(80°C, 24 h). Purification by chromatography (Pentane/EtOAc: 90/10 v/v) afforded the title compound
3i. Orange solid (445 mg, yield = 86%); m.p. 142°C; 1H-NMR (CDCl3, 500 MHz, δ/ppm) 8.20 (dd, J =
8.0 Hz, 1H), 8.17 (d, J = 8.2 Hz, 2H), 8.01 (d, J = 7.9 Hz, 1H), 7.94 (d, J = 8.3 Hz, 2H), 7.72 (d, J = 8.4
Hz, 2H), 7.62 – 7.38 (m, 7H), 7.33 (t, J = 7.4 Hz, 2H), 1.90 (s, 6H); 13C-NMR (CDCl3, 125 MHz,
δ/ppm) 170.0, 164.0, 158.0, 153.0, 140.5 (CH), 140.3, 139.4, 135.2, 134.6, 129.5 (2 x CH), 127.2 (2 x
CH), 126.3 (CH), 126.1 (2 x CH), 125.6 (CH), 123.7, 123.6 (CH), 123.2 (CH), 120.2 (2 x CH), 117.9,
109.7 (2 x CH), 99.9 (CH), 85.4, 27.3 (2 x CH3); IR (ν/cm-1) 1736, 1595, 1574, 1513, 1448, 1333, 1313,
1269, 1226, 1170, 1143, 1026, 748, 723; HRMS (ESI+) calcd for C33H25N2O2S [M+H]+: 513.1631,
found: 513.1631; UV-Vis (CH2Cl2) λmax = 417 nm (ε = 20 630 L.mol-1.cm-1).
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2.3
Crystallography
Single crystals suitable for X-ray diffraction were grown by slow diffusion of diisopropylether in
concentrated chloroform solution. CCDC 1560148 (1a), 1560149 (1b), 1564219 (1d), 837775 (1e),
1578107 (1g), 1560145 (1i), 1560146 (2b), 1564223 (2i), 1560147 (2j) and 1560150 (3f) contains the
supplementary crystallographic data for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
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2.4
Spectroscopic measurements and solid-state fluorescence
Absorption spectra were recorded on a JASCO V670 spectrophotometer. Fluorescence spectra
(excitation and emission) were measured using a Horiba-Jobin Yvon Fluorolog-3 spectrofluorimeter
equipped with a Hamamatsu R928 photomultiplier tube. Spectra were reference corrected for both the
excitation source light intensity variation (lamp and grating) and the emission spectral response
(detector and grating). All solvents were of spectrophotometric grade. Coumarine 153 and Rubrene
were purchased from Acros. Solid-state measurements were performed using a calibrated integrative
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sphere collecting all the emission (2π steradians covered with spectralon®), model F-3018 from Horiba
Jobin Yvon. Because the emission tails extend far in the red emission range, the spectrofluorimeter
detector response was checked by recording the emission of known red emitting compounds (4-
(dimethylamino)-nitrostilbene, tetraphenylporphyrin and rhodamine 6G) and calibrated in
consequence.[60] Absolute quantum yields were measured as previously reported.[41]
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2.5
Agregation-induced Emission Measurements
Stock solutions (1 mM) of the desired compound were prepared in acetone. For each water fraction (fw),
100 µL of this solution were added in a 2 mL volumetric flask, followed by the required volume of
acetone. Water was then added one-shot to reach 2 mL.
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3. Results and Discussion
3.1 Syntheses

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Scheme 1. Structures of activated methylene compounds A-J and synthesis of fluorophores 1a-1h, 2a-
2j and 3b-3i.
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All compounds 1a – 3i were prepared in moderate to good yield by a Knoevenagel condensation
between 4-(diphenylamino)benzaldehyde 1, 9-ethyl-9H-carbazole-3-carboxaldehyde 2 or 4-(9H-
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carbazol-9-yl)-benzaldehyde 3 and the corresponding activated methylene compounds A - J in ethanol
or acetonitrile in presence of catalytic amount of piperidine (Scheme 1). Conventional or microwave
heating are used. Indanedione A and the 2-substitued acetonitrile derivatives B - D are commercially
available. Dicyanoisophorone E was obtained from malonitrile and isophorone according to published
procedure, whereas the 2(5H)-furanone ring TCF F was synthesized from malononitrile and 3-hydroxy-
3-methyl-butan-2-one 4 with lithium ethoxide in ethanol as a base (Scheme 2).[61] Compounds G - J
are 2-substituted-∆αβ-butenolide derivatives. The αβ-unsaturated-γ-lactone ring, also known as ∆αβ-
butenolide or 2(5H)-furanone, is a structural motif largely found in natural products such as vitamin C,
cardenolide alkaloids or annonaceous acetogenin, to cite a few.[62-66] Therefore, substituted 2(5H)-
furanone rings are interesting building blocks in organic chemistry and their syntheses have been largely
investigated.[67-72] 4,5,5-trimethyl-2(5H)-furanone substituted at position C2 are obtained from 3-
hydroxy-3-methyl-butan-2-one 4 as shown in Scheme 2. Thus, compounds G [68] and H [69] were
obtained from 4 and ethyl cyanoacetate or dimethyl malonate, respectively, in presence of a catalytic
amount of sodium methoxide in methanol. Subsequent reaction of G with 2-aminothiophenol in
phosphoric acid afforded I in 66 % yield.[70] J was obtained in two steps from ethyl 2-bromoacetate by
nucleophilic substitution with sodium sulfinate [53] followed by condensation with 4 in presence of
sodium methoxide in methanol. The structures of all compounds 1a - 3j were unambiguously assigned
by 1H and 13C NMR. Although two isomers could potentially arise from the Knoevenagel condensation,
the observation of one set of signals in the NMR spectra for the protons connected to the central C=C
3
bond, consisting of one singlet or two doublets along with a J coupling constant of 16 Hz, confirmed
the stereoselective formation of the Z-isomers only for α-cyanostyrene derivatives (i.e. 1b-1d, 2b-2d,
and 3b) and of the E-isomer for the other styryl-derivatives (i.e. 1e-1i, 2f-2j, and 3f-3i).
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CN
O
O
O
CN
F
Na, dry MeOH, 0°C
then AcOH
CN
Li cat, dry EtOH
, 18 h
CN
H2N
HS
62 %
H3PO4
, 10 h
O
G
NC
NC
CN
82 %
O
O
PhSO2Na
DMF, rt, 24 h
O
O
S
S
O
O
Br
O
O
I
HO
O
71 %
N
O
68 %
4
NaOMe, dry MeOH
, 18 h
NaOMe, dry MeOH
r.t., 2 h
O
O
O
O
O
O
O
O
H
O
S
J
O
59 %
66%
O
O
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Scheme 2. Synthesis of the electron-accepting groups F - J from 3-hydroxy-3-methyl-butan-2-one 4.
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3.2 Photophysical Properties in Solution
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450
451
452
453
454
455
456
457
The absorption spectra of all compounds were measured in diluted dichloromethane solutions.
Relevant photophysical data are reported in Table 1. The spectra displayed in Figures 1 and SI-19 to SI-
21 showed typical induced charge transfer transitions in the visible with bands positions varying
accordingly with the strength of the substituent groups. For a given electron-donating group, increasing
the electron-acceptor strength induced a red-shift of the absorption maxima: λmax shifted from 427 nm
for 1c to 565 nm for 1f bearing the strongest electron-withdrawing group in the 4-(N,N-
diphenylamino)phenyl series, from 389 nm for 2c to 510 nm for 2f in the 9-ethyl-9H-carbazolyl series,
and from 397 nm for 3h to 481 nm for 3f in the 4-(9H-carbazol-9-yl) series. In all cases, the strongest
electro-accepting group F led to the most red-shifted absorption. Upon excitation in the main absorption
band only a weak fluorescence was observed for most compounds likely because of radiationless decay
from TICT excited states (Figures 1, SI-22 to SI-24). Only compounds 1a, 1e, 1g, 1h, 1i, 3g, and 3i

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displayed significant emission (Φ > 2%), up to 20% at 689 nm for 1e. This low emission could be
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anticipated especially for molecules built on the α-cyano-stilbene motif (1b, 1c, 1d, 2b, 2c, 2d, 3b) that
undergo very efficient non-radiative de-excitations via twisted conformations of chromophores in
solution, torsional movements around the central C=C double bond [73-76] or cis-trans
isomerization.[77] Emissions are characterized by large Stokes’ shifts ranging from 1328 cm-1 for 2a to
9462 cm-1 for 3b, typical of an excited state charge transfer and of high difference between dipole
moments in ground and excited states. Even though this is not the object of the present article, this latter
parameter is important in view of obtaining large biphotonic fluorescence efficiencies, a plus for
potential biological applications. On the other hand, the emission maxima on the other hand ranged
from 502 nm (2d) to over 700 nm for the most red-shifted compounds 1b (717 nm), 1f (746 nm) and 3f
(712 nm). Given the importance of NIR emission for deep in vivo imaging,[78] such long emission
wavelengths are interesting in spite of the low emission quantum yields, particularly for such small
molecular weight molecules (molecular weight below 460 g.mol-1).
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Figure 1. Absorption and emission spectra in dilute solution (CH2Cl2) for selected compounds.

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Table 1. Spectroscopic data in dilute solution (CH2Cl2) and in the crystal state for all compounds.
Solution in CH2Cl2
Crystal state [c]
Compound
λabs / nm
Φ [a] / %
λem / nm
Φ [d] / %
∆ν
/
cm-1 [b]
λem / nm
(ε / L.mol-1.cm-1)
485 (37800)
456 (28700)
427 (29700)
454 (31200)
490 (23600)
565 (42000)
484 (38400)
455 (34900)
455 (34900)
453 (44800)
405 (21300)
389 (25000)
417 (20300)
510 (24000)
413 (22590)
452 (22600)
439 (26100)
404 (21110)
481 (29700)
421 (21070)
397 (23200)
417 (20630)
644
717
572
539
689
746
656
636
633
482
616
471
502
613
576
533
546
654
712
628
593
583
2
5091
7983
5937
3474
5894
4294
5417
6255
5054
1328
8458
4476
4060
3295
6852
3362
4464
9462
6745
7829
8326
6828
618
669
640
647
n.a.
n.a.
645
640
673
599
603
551
619
768
583
614
598
596
735
622
534
603
11
4
1a
1b
1c
1d
1e
1f
<1
<1
<1
20
1
23
18
n.a.
n.a.
9
6
1g
1h
1i
3
10
19
18
28
10
11
4
7
<1
<1
<1
<1
2
2a
2b
2c
2d
2f
<1
<1
<1
<1
<1
6
8
2h
2i
34
33
11
11
24
24
12
2j
3b
3f
3g
3h
3i
2
4
[a]
[b]
477
478
Using Rubrene in methanol as reference (Φ = 27%) or Coumarine 153 in methanol (Φ = 54%).
Stokes’ shifts. [c] In crystalline powder. [d] Using a calibrated integrated sphere.
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3.2 Aggregation-Induced Emission
Aggregation-induced emission (AIE) fluorophores typically showed an increase in fluorescence
intensity from the non-fluorescent or weakly fluorescent molecule in dilute organic solution to the
strongly fluorescent suspension of nanoparticles that formed when water is added to the solvent. Good

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AIE properties may be expected from solids that are strongly emissive in their crystalline state, although
the emission wavelength and efficiency can be different, as we already noticed.[41]
The AIE behavior of some compounds was studied by recording the emission spectra obtained from
acetone/water mixtures of fluorophores at the same concentration (10 µM), but with different volume
fractions of water (fw). The fluorescence of push-pull dipolar D-π-A compounds is usually weaker in
polar solvents because enhanced electrostatic interactions with the chromophore strongly polarized ICT
excited state. So as expected, the emission in pure acetone (fw = 0) is significantly decreased in
comparison with dichloromethane. The emission is further quenched when fw was increased from 0 to
50-60% where the solvating power of the solvent mixture is still sufficient to dissolve the compounds
and prevent aggregation, due to the higher polarity of the solvent system. Then, when fw was gradually
increased from 60% volume fractions of water to 95%, the products start to aggregate and form
nanoparticles, whereas the fluorescence intensity increased considerably. Remarkably, all the
compounds studied showed AIE, but noticeable differences could be evidenced as illustrated in Figure 2
and SI-25 to SI-35. On the other hand, the emission maxima of nanoparticles underwent a blue-shift
with respect to pure acetone solution, for all compounds except 1d (Fig. SI-28) and 2a (Fig. SI-33). The
maximum emission intensity was reached between 80 and 95% water volume fractions depending on
the compound. In most cases, a decrease of the fluorescence intensity can be seen at higher fw. The
overall increase of fluorescence between solutions and nanoparticles (αAIE) was of the order of α = 3-
AIE
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20 but could reach values higher than 100 for some compounds. Remarkable increases of more than 348
and 960 were obtained for 3g and 3f respectively, the most interesting compounds. This is reflected by
the quantum yield values of nanoparticles, generally comprised between 2% and 8%, except for 3f for
which a noteworthy 20% quantum yield value at 678 nm was obtained, to be compared with the values
measured in dichloromethane solution. It has to be noted that 1i and 3g are as fluorescent in their
dissolved form in dichloromethane than in nanoparticles. Note that these results are in perfect agreement
with those previously reported for compound 2a (λem = 630 nm for a 15% quantum yield), although the

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initial solvent used was not the same (THF instead of acetone here).[39]
511 Table 2. Optical properties in nanoparticles (acetone/water mixture).
Nanoparticles (acetone/water) [a]
Compound
λabs / nm
λem / nm
α
Φ / %
AIE
493
635
106
8
1a
1b
1c
1d
1e
1f
467
437
664
595
3
< 1
20
20
9
2
450
649
4
490
698
3
544
749
17
136
9
< 1
489
659
6
1g
1i
465
625
4
493
468 (460)[b]
636
630 (630)[b]
59
105
969
348
17
5
1h
2a
3f
n.d (15%)[b]
580
678
20
8
425
616
3g
3i
420
590
6
[a]
[b]
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In acetone/water at fw giving the maximum emission. according to [39]. THF solution was used
instead of acetone.
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Figure 2. Emission spectra in acetone/water mixture of different water fraction (fw), and change of the
peak intensity with fw for 1g (a) and 3f (b), c=10µM.
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523
3.3 Emission in the Crystal State
Encouraged by the observations made in nanoparticles, we then turned our attention to the study of
the emission in the crystal-state (micrometric powders). All compounds with the exception of 1e and 1f
displayed an intense orange-red emission in their crystalline form under illumination by a handled UV
lamp at 365 nm, visible to the naked eye. Emission and excitation spectra as well as fluorescence

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quantum yields were therefore measured using a calibrated integrating sphere. Emission spectra are
given in Figure 3 and in the Supporting Information (Figures SI-36 to SI-38) and data summarized in
Table 1. In the crystal state, the emission was, in most cases, significantly red-shifted relative to the
emission in solution in dichloromethane, 20 to 60 nm and up to 115 nm for compound 2d displaying an
emission maximum at 620 nm. Compounds 1a, 1b, 2b and 3b, for which a small blue shift (20 to
45 nm) was observed, were of notable exception. However, as expected, the strongest electron-
accepting group (TCF) induces the maximum red-shift (compounds 2f and 3f having emission above
700 nm). The emission quantum yields were considerably increased though, reaching 34% at 614 nm
for the most emissive compound 2i and 11% at 735 nm for 3f, which is remarkable for such small
molecule.
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Figure 3. Crystal-state fluorescence spectra of selected compounds showing the tuning of emission
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wavelengths spanning the entire visible range.

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3.4 Crystal structures
Although no study has directly linked the solid-state fluorescence properties to the crystalline
structure, several have nevertheless pointed out that emission in solid may depend on the arrangements
of the molecules in the crystal.[27, 79] Thus, on dipolar structure similar to those presented here, we
have been able to show that certain patterns like ladder-like, brickwork or herringbone patterns could be
observed in the crystal packing of emissive compounds, in which the molecules are slipped away with
respect from one another preventing close packing.[40, 41] Conversely, the same studies associated the
lack of crystal-state emission to the presence of closely packed face-to-face H-type dimers in the crystal
structure. This was perfectly illustrated by the example of compounds 1e, for which two molecules lie at
short distance with respect to one another (3.587 Å) with strong π-π interactions (Figure 4).[40]
So knowledge of the crystal-state structure and the associated molecular packing could nevertheless
help understanding the origin of the solid-state emission. To that end single crystals were grown by slow
diffusion of a non-solvent (diisopropylether) in concentrated chloroform or dichloromethane solutions.
Thus, we obtained sub-millimeter size crystal suitable for X-ray diffraction for nine new compounds
over twenty-two synthesized and the structures were resolved (compounds 1a, 1b, 1d, 1g, 1i, 2b, 2j, 2i
and 3f). Crystallographic data and refinement parameters are given in Table 3, SI-2 and SI-3, whereas
basic structural parameters, selected distances and dihedral angles are compiled in SI (Table SI-1)
together with atom numbering schemes with the angles and distance definitions (Figure SI-1). ORTEP
views with 50% probability are shown in Figures SI-2 to SI-10.

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Figure 4. Compound 1e, stacked dimer (left) and crystal packing view along the crystallographic a axis
(right).
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Compounds 1a and 1d crystallize in the P 1 triclinic space group. Compounds 1b, 1e, 1g, 1i, 2i and
2j crystallize in the P21/n or P21/c monoclinic space groups. 2b and 3f crystallize in the non-
centrosymmetric orthorhombic Fdd2 and monoclinic P21 space groups respectively. The asymmetric
units are composed of one molecule, except for 1d and 1g where two crystallographically independent
molecules are present. As already observed for related dipolar molecules [40, 44, 80-82] or N,N-diethyl
analogues,[40, 83] the molecular structures are very similar for all compounds with an almost planar π-
conjugated system indicating a full conjugation between the donor and the acceptor end. Only the
acceptor end of the dipole is slightly twisted with a dihedral angle measured between the main plane and
the electron-accepting ring of 31.5° for the most distorted structures 1g and 2j, which is bend with a
14.4° angle between the 2(5H)-furanone ring mean plane and the carbazole ring mean plane. As
expected the two phenyl groups on the N-donor atom are not coplanar with the main molecular plane for
steric reasons but adopt a propeller type conformation.[25, 33] Such a conformation is not possible for