Singlet oxygen is an emissive ligand.

Unprecedented experimental evidence shows that gaseous singlet oxygen (1O2) acts as an emissive ligand following collisional photosensitization. This evidence was obtained by monitoring 1O2 phosphorescence intensity at ≈1275-1280 nm and the excited state lifetime of singlet oxygen generated by known tetraphenylporphyrin photosensitizers, while varying the atmospheric environment.

The Excited-State N-H Tautomerization Rate in Free-Base Corroles.

Corrole is a tetrapyrrolic dye with a structure that resembles porphyrin, apart from a single missing carbon. The absence of this carbon results in the re-arrangement of the double bonds within the macrocycle, and the presence of three pyrrolic protons in the central cavity in its free base form. These protons lead to the existence of two distinct tautomeric structures that exist in a dynamic equilibrium. Although the ground state energies of the tautomers are similar, the excited states show a significant difference in energy which unbalances the equilibrium between the tautomers and results in rapid excited state tautomerization, favouring one tautomeric species over the other. Although the excited state tautomerization process has been known for a long time, very few studies have been performed on it leaving many key aspects of the process poorly understood. Herein we show how ultrafast photoluminescence can be used to experimentally determine the rates of excited state tautomerization and activation energies of three free base corrole derivatives thus allowing us to completely describe the excited state dynamics of the unusual, excited state of free base corrole and opening the door to the development of new materials that can exploit it unique characteristics..

Statistical Analysis of Copper(I) Iodide and Bis(Diphenylphosphino)alkane-Based Complexes and Coordination Polymers.

The prediction of the metal cluster within a coordination polymer or complex, as well as the dimensionality of the resulting polymer or complex (i.e., 0D, 1D, 2D, or 3D), is often challenging. This is the case for Ph2P(CH2)mPPh2 ligands (1 ≤ m ≤ 8) and CuX salts, particularly for X = I. This work endeavors a systematic statistical analysis combining studies in the literature and new data, mapping the nature of the resulting CuI aggregates with eight different diphoshphines in 2:1, 3:2, 1:1, 2:3, and 1:2 CuI:Ph2P(CH2)mPPh2 molar ratios as a function of m, which lead to either pure products or mixtures. Several trends are made relating stoichiometry and chain length to the CuI cluster formed (i.e., globular vs. quasi-planar). Four new X-ray structures were determined: [Cu3I2(L1)3]I, Cu3I3(L2)2, Cu2I2(L6)2, and Cu4I4(L8)2, where m is, respectively, 1, 2, 6, and 8, in which the CuxIy central aggregates adopt triangular bipyramid, diamond, rhomboid, and cubane shaped motifs, respectively. Photophysical measurements assisted the establishment of trends considering the paucity of the crystallographic structures. During this study, it was also found that the 0D-complex Cu2I2(Ph2P(CH2)5PPh2)2 exhibits thermally activated delayed fluorescence.

Truxene-to-Fluorenone Energy Transfer in a Robust Mesoporous Zn-MOF.

A new metal-organic framework (MOF; [Zn4O(hett)4/3(fluo)1/2(bdc)1/2]n; TFT-MOF) constructed on chromophoric ligands 5,5',10,10',15,15'-hexaethyltruxene-2,7,12-triacetate (hett), 9-fluorenone-2,7-dicarboxylate (fluo), terephthalate (bdc), and the Zn4O node has been prepared and identified by powder X-ray diffraction. This luminescent MOF exhibits large mesoporous pores of 2.7 nm based on computer modeling using density functional theory (DFT) calculations. The steady-state and time-resolved fluorescence spectra and photophysical parameters of TFT-MOF have been investigated and compared with those of the free ligands and their basic chromophores. All in all, TFT-MOF exhibits particularly efficient singlet-singlet energy-transfer processes described as 1(hett)* → (fluo) and 1(bdc)* → (fluo), leading to fluorescence arising for the fluo lumophore operating only through Förster resonance energy transfer (FRET) with an efficiency of transfer of up to >95%. This experimental conclusion was corroborated by DFT and time-dependent DFT (TDDFT). For the 1(hett)* → (fluo) process, the approximated overall rate constant of energy transfer was evaluated to be at most 2.04 × 1010 s-1 (using a Stern-Volmer approach of solution data and the relationship between distance and concentration). This process was analyzed using the Förster theory, where two intrapore energy transfer paths of center-to-center distances of 13 and 25 Å have been identified. TFT-MOF photosensitizes the formation of singlet oxygen (1O2 (1Σg)) as detected by its phosphorescence signal at 1275 nm.

Strong Host-Guest Dependence on the Emissive Properties of MOF-5 and [Zn2(BTTB)(DMF)2•(H2O)3]n.

3D-[Zn4O(1,4-BDC)3•x(solvent)]n (MOF-5; BDC = 1,4-benzodicarboxylate) and 3D-[Zn2(BTTB)(DMF)2•(H2O)3]n (MOF-D; BTTB = 4,4',4″,4‴-benzene-1,2,4,5-tetrayltetrabenzoate) have been investigated by means of steady-state UV-visible and fluorescence and time-resolved emission spectroscopy, as a function of solvent and power of the excitation irradiation. The low-temperature X-ray structures (173 K) were permitted to locate solvent molecules (here H2O) in the lattice. They were found distributed in the middle in the voids with no evidence of specific interactions (H-bond, coulombic, and dipole-dipole) with the framework. The fluorescence decays of the ligands (ππ* excited state), τF, for the host-guest composites MOF-5@solvent and MOF-D@solvent (solvent = air, MeCN, EtCN, MeOH, EtOH, and DMF) were found bi-exponential (short τF1 (ps), and long τF2 (ns)) with one important feature: upon cooling from 298 to 77 K, MOF-5's τF1 decreases and τF2 increases, while the opposite trend is generally observed in MOF-D. The low values for τF1 (ps) in MOF-5 are associated with the augmented probability of solvent-ligand collisions leading to nonradiative deactivation, which upon cooling to 77 K increases further as the scaffolding contracts. The augmentation in τF2 is readily associated with the increased rigidity of the ligands that are not submitted to this effect (at the surface of the MOF and as pendent groups). For the low emitter MOF-D, the reversed situation is noted but not as clearly due to the uncertainties in the data. Upon increasing the excitation flux, the fluorescence intensity increases linearly with the laser power indicating the absence of singlet-singlet annihilation, inferring the absence of efficient exciton migration. This observation is explained by the small absorptivity coefficients, which leads to a small J spectral overlap between absorption and fluorescence according to the Forster and Dexter theories, and consequently, a small rate for energy migration. This conclusion drastically changes the perception of the photocatalytic mechanism of MOF-5 and other MOFs exhibiting similar absorption features (i.e., no antenna effect).

S-Heptazine N-ligand based luminescent coordination materials: synthesis, structural and luminescent studies of lanthanide-cyamelurate networks.

Various series of lanthanide metal-organic networks denoted Ln-Cy (Ln = La, Ce, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb), were synthesized under solvothermal conditions using potassium cyamelurate (K3Cy) and lanthanide nitrate salts. All obtained materials were fully characterized, and their crystal structures were solved by single-crystal X-ray diffraction. Four types of coordination modes were elucidated for the Ln-Cy series with different Ln3+ coordination geometries. Structural studies were performed to compare the various coordination compounds of the Ln-Cy series. Moreover, the cyamelurate linkers of rich π-conjugated and uncoordinated Lewis basic sites were used as an absorbing chromophore to enhance the luminescence quantum efficiency, the band emission and the luminescence lifetime of the coordinated Ln metal centers. Solid-state UV-visible measurements combined with density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations were performed to further explore luminescent features of the Ln-Cy series and their origins.

Chain Length Effect on the Structural and Emission Properties of the CuI/Bis((4-methoxyphenyl)thio)alkane Coordination Polymers.

A systematic chain length variation of the ligand para-MeOC6H4S(CH2)mSC6H4OMe (1 ≤ m ≤ 8) was performed to study its effect on the structures and photophysical properties of the coordination polymers (CP) when reacted with CuI. Indeed, direct correlations are noted between these features and m. When m is an odd number, the secondary building unit is systematically the common closed-cubane Cu4I4 cluster, rendering the material strongly luminescent (i.e., emission quantum yield, Φe > 20%), and the CP is one-dimensional (1D). However, when m is 2, 4, and 6, the SBUs exhibit rare polymeric motifs of (Cu2I2)n: staircase ribbon, fused poly(rhombic pseudo-dodecahedron), and accordion ribbon, respectively, and the emission intensities are either very weak (Φe < 0.001%) or of medium intensity (Φe ∼ 10% when m = 6). When m = 8 (i.e. the most flexible chain), the SBU is a closed-cubane Cu4I4 and the emission intensity is medium (Φe ∼ 10%). A special case was observed for m = 3, where a co-crystallization of the molecular cluster Cu4I4(NCCH3)4 is observed in the lattice, which turns out to be quite important for the stability of the network.

A Fused Poly(truncated rhombic dodecahedron)-Containing 3D Coordination Polymer: A Multifunctional Material with Exceptional Properties.

The design of new and inexpensive metal-containing functional materials is of great interest. Herein is reported a unique thermochromic near-IR emitting coordination polymer, 3D-[Cu8I8(L1)2]n, CP2, which is formed when ArS(CH2)4SAr (L1, Ar = 4-C6H4OMe) reacts with 2 equiv of CuI in EtCN. In MeCN, CP1 ([Cu4I4(L1)(MeCN)2]n, consisting of an alternating [-Cu4I4-L1-Cu4I4-L1-]n chain where the Cu4I4 cubane units bear two metal-bound MeCN molecules, is formed. Heat-driven elimination of these MeCN's in solid CP1 also leads to CP2 through a predisposed organization of the Cu4I4 units prone to fusion after MeCN eliminations (i.e., a rare case of template effect). The CP2 structure exhibits parallel 1D-(Cu8I8)n chains, (z-axis; designated 1D-[CuI]n) as secondary building units (SBU) held together by parallel thioether ligands (x,y-axes), forming a nonporous 3D network. The structure of this 1D-[CuI]n SBU is unprecedented and consists of a series of fused and twisted open Cu4I4 cubanes forming a fused poly(truncated rhombic dodecahedron). Unexpectedly, the compact 3D CP2 exhibits a solid-to-solid phase transition at 100 °C and a hysteresis of ∼20 °C. CP1 emits intensively (298 K: λemi = 564 nm; Φe = 0.35), whereas CP2 presents a strongly red-shifted weaker emission (298 K: λemi ∼ 740 nm, Φe < 0.0001). Moreover, CP2, which is stable over long periods of time, exhibits thermochromism where the emission intensity of the near-IR band decreases significantly at the benefit of a ligand-centered phosphorescence at 415 nm. Altogether, these properties listed above make CP2 exceptional. The low-energy singlet and triplet excited states have been assigned to ligand/metal-to-ligand charge transfer based on DFT and TD-DFT computations.

New phosphorescent iridium(III) dipyrrinato complexes: synthesis, emission properties and their deep red to near-infrared OLEDs.

A series of heteroleptic Ir(iii) complexes composed of two cyclometalated C^N ligands and one dipyrrinato ligand used as an ancillary ligand are synthesized and characterized. With the introduction of a fluorine atom, phenyl ring or diphenylamino group into both C^N ligands and by keeping the ancillary ligand unchanged, these Ir(iii) dipyrrinato phosphors do not show an obvious shift in their emission bands. They exhibit emissions extending well into the near-infrared region with an intense band located at around 685 nm in both photo- and electroluminescence spectra, and the deep red to near-infrared organic light emitting diodes (OLEDs) based on them afforded a maximum external quantum efficiency of 2.8%. Density functional theory (DFT) calculations show that both the electronic contributions on the lowest unoccupied molecular orbitals (LUMOs) and the highest energy semi-occupied molecular orbitals (HSOMOs) are mainly localized on the dipyrrinato ligand, indicating that the ancillary ligand, which remains unchanged in this series, exhibits a lower triplet state energy in the iridium phosphors than those involving the C^N ligands. Therefore a switch from "(C^N)2Ir" to dipyrrinato ligand-based emission is observed in these iridium(iii) complexes.

Porphyrin-Containing MOFs and COFs as Heterogeneous Photosensitizers for Singlet Oxygen-Based Antimicrobial Nanodevices.

Visible-light irradiation of porphyrin and metalloporphyrin dyes in the presence of molecular oxygen can result in the photocatalytic generation of singlet oxygen (1O2). This type II reactive oxygen species (ROS) finds many applications where the dye, also called the photosensitizer, is dissolved (i.e., homogeneous phase) along with the substrate to be oxidized. In contrast, metal-organic frameworks (MOFs) are insoluble (or will disassemble) when placed in a solvent. When stable as a suspension, MOFs adsorb a large amount of O2 and photocatalytically generate 1O2 in a heterogeneous process efficiently. Considering the immense surface area and great capacity for gas adsorption of MOFs, they seem ideal candidates for this application. Very recently, covalent-organic frameworks (COFs), variants where reticulation relies on covalent rather than coordination bonds, have emerged as efficient photosensitizers. This comprehensive mini review describes recent developments in the use of porphyrin-based or porphyrin-containing MOFs and COFs, including nanosized versions, as heterogeneous photosensitizers of singlet oxygen toward antimicrobial applications.

The TDDFT Excitation Energies of the BODIPYs; The DFT and TDDFT Challenge Continues.

The derivatives of 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) are pivotal ingredients for a large number of functional, stimuli-responsive materials and therapeutic molecules based on their photophysical properties, and there is a urgent need to understand and predict their optical traits prior to investing a large amount of resources in preparing them. Density functional theory (DFT) and time-dependent DFT (TDDFT) computations were performed to calculate the excitation energies of the lowest-energy singlet excited state of a large series of common BODIPY derivatives employing various functional aiming at the best possible combination providing the least deviations from the experimental values. Using the common "fudge" correction, a series of combinations was investigated, and a methodology is proposed offering equal or better performances than what is reported in the literature.

2-Azabutadiene complexes of rhenium(I): S,N-chelated species with photophysical properties heavily governed by the ligand hidden traits.

The reaction of [Re(CO)3(THF)(µ-Br)]2 or [Re(CO)5X] (X = Cl, Br, I) with the diaryl-2-azabutadienes [(RS)2C[double bond, length as m-dash]C(H)-N[double bond, length as m-dash]CAr2] containing two thioether arms at the 4,4-position forms the luminescent S,N-chelate complexes fac-[(OC)3ReX{(RS)2C[double bond, length as m-dash]C(H)-N[double bond, length as m-dash]CAr2}] (1a-h). The halide abstraction by silver triflate converts [(OC)3ReCl{(PhS)2C[double bond, length as m-dash]C(H)-N[double bond, length as m-dash]CPh2}] (1c) to [(OC)3Re(OS([double bond, length as m-dash]O)2CF3){(PhS)2C[double bond, length as m-dash]C(H)-N[double bond, length as m-dash]CPh2}] (1j) bearing a covalently bound triflate ligand. The cyclic voltammograms reveal reversible S^N ligand-centred reduction and irreversible oxidation waves for all complexes. The crystal structures of nine octahedral complexes have been determined along with that of (NaphtylS)2C[double bond, length as m-dash]C(H)-N[double bond, length as m-dash]CPh2 (L6). A rich system of weak non-covalent intermolecular secondary interactions through CHX(Cl, Br)Re, CHO, COπ(Ph), CHπCO, CHO and CHS contacts has been evidenced. The photophysical properties have been investigated by steady-state and time-resolved absorption (fs transient absorption, fs-TAS) and emission (ns-TCSPC and ps-Streak camera) spectroscopy in 2-MeTHF solution at 298 and 77 K. The emission bands are composed of either singlet (450 < λmax < 535 nm) and/or triplet emissions (at 77 K only, λmax < 640 nm, or appearing as a tail at λ > 600 nm), which decay in a multiexponential manner for the fluorescence (short ps (i.e.

Design of P-Chirogenic Aminophosphine-Phosphinite Ligands at Both Phosphorus Centers: Origin of Enantioselectivities in Pd-Catalyzed Allylic Reactions.

We have recently patented an unprecedented stereospecific N → O phosphinyl migration process which transforms P-chirogenic aminophosphines into phosphinites. A fine design of aminophosphine phosphinite ligands (AMPP*) derived from ephedrine and bearing a P-chirogenic center either at the aminophosphine or phosphinite moiety was performed. The synthesis of AMPP* ligands with a P-chirogenic aminophosphine moiety was based on the well-established stereospecific reaction of oxazaphospholidine borane with organolithium reagents, followed by trapping with a chlorophosphine and borane decomplexation. Concurrently, the preparation of AMPP* ligands with a P-chirogenic phosphinite moiety was performed by N → O phosphinyl migration of aminophosphines borane by heating at 50 °C with DABCO and then reaction with chlorophosphines. AMPP* ligands were studied in palladium-catalyzed asymmetric allylic alkylations, leading to enantioselectivities from 91% (R) to 95% ee (S). X-ray crystallographic data for relevant Pd-AMPP* complexes and computer modeling explained the origin of the enantioselectivities based on MO interactions of most stable conformers with nucleophiles.

From Short-Bite Ligand Assembled Ribbons to Nanosized Networks in Cu(I) Coordination Polymers Built Upon Bis(benzylthio)alkanes (BzS(CH2)nSBz; n = 1-9).

With the objective to establish a correlation between the spacer distance and halide dependence on the structural features of coordination polymers (CPs) assembled by the reaction between CuX salts (X = Cl, Br, I) and dithioether ligands BzS(CH2)nSBz (n = 1-9; Bz = benzyl), a series of 26 compounds have been prepared and structurally investigated. A particular attention has been devoted to the design of networks with extremely long and flexible methylene spacer units between the SBz donor sites. Under identical conditions, CuI and CuBr react with BzSCH2Bz (L1) affording respectively the one-dimensional (1D) CPs {Cu(µ2-I)2Cu}(µ-L1)2]n (CP1) and {Cu(µ2-Br)2Cu}(µ-L1)2] (CP2), which incorporate Cu(µ2-X)2Cu rhomboids as secondary building units (SBUs). The hitherto unknown architecture of two-dimensional (2D) layers obtained with CuCl (CP3) differs from that of CP1 and CP2, which bear inorganic -Cl-Cu-Cl-Cu-Cl- chains interconnected through bridging L1 ligands, thus forming a 2D architecture. The crystallographic characterization of a 1D CP obtained by reacting CuI with 1,3-bis(benzylthio)propane (L2) reveals that [{Cu(µ2-I)2Cu}(µ-L2)2]n (CP4) contains conventional Cu2I2 rhomboids as SBUs. In contrast, unusual isostructural CPs [{Cu(µ2-X)}(µ2-L2)]n (CP5) and (CP6) are obtained with CuX when X = Br and Cl, respectively, in which the isolated Cu atoms are bridged by a single µ2-Br or µ2-Cl ion giving rise to infinite [Cu(µ2-X)Cu]n ribbons. The crystal structure of the strongly luminescent three-dimensional (3D) polymer [{Cu4(µ3-I)3(µ4-I)(µ-L3)1.5]n (CP7) issued from reacting 2 equiv of CuI with BzS(CH2)4SBz (L3) has been redetermined. CP7 features unusual [(Cu4I3)(µ4-I)]n arrays securing the 3D connectivity. In contrast, mixing CuI with an excess of L3 provides the nonemissive material [{Cu(µ2-I)2Cu}(µ-L3)2]n (CP8). Treatment of CuBr and CuCl with L3 leads to [{Cu(µ2-Br)2Cu}(µ-L3)2]n (CP9) and the 0D complex [{Cu(µ2-Cl)2Cu}(µ-L3)2] (D1), respectively. The crystallographic particularity for CP9 is the coexistence of two topological isomers within the unit cell. The first one, CP9-1D, consists of simple 1D ribbons running along the a axis of the unit cell. The second topological isomer, CP9-2D, also consists of [Cu(µ2-Br)2Cu] SBUs, but these are interconnected in a 2D manner forming 2D sheets placed perpendicular to the 1D ribbons. Four 2D CPs, namely, [{Cu4(µ3-I)4}(µ-L4)2]n (CP10), [{Cu(µ2-I)2Cu}(µ-L4)2]n (CP11), [{Cu(µ2-Br)2Cu}(µ-L4)2]n (CP12), and [{Cu(µ2-Cl)2Cu}(µ-L4)2]n (CP13), stem from the self-assembly process of CuX with BzS(CH2)6SBz (L4). A similar series of 2D materials comprising [{Cu4(µ3-I)4}(µ-L5)2]n (CP14), [{Cu(µ2-I)2Cu}(µ-L5)2]n (CP15), [{Cu(µ2-Br)2Cu}(µ-L5)2]n (CP16), and [{Cu(µ2-Cl)2Cu}(µ-L5)2]n (CP17) result from the coordination of BzS(CH2)7SBz (L5) on CuX. Ligation of CuX with the long-chain ligand BzS(CH2)8SBz (L6) allows for the X-ray characterization of the luminescent 2D [{Cu4(µ3-I)4}(µ-L6)2]n (CP18) and the isostructural 1D series [{Cu(µ2-X)2Cu}(µ-L6)2]n CP19 (X = I), CP20 (X = Br) and CP21(X = Cl). Noteworthy, BzS(CH2)9SBz (L7) bearing a very flexible nine-atom chain generated the crystalline materials 2D [{Cu4(µ3-I)4}(µ-L7)2]n (CP22) and the isostructural 1D series [{Cu(µ2-X)2Cu}(µ-L6)2]n CP23 (X = I), CP24 (X = Br), and CP25 (X = Cl), featuring nanometric separations between the cubane- or rhomboid-SBUs. This comparative study reveals that the outcome of the reaction of CuX with the shorter ligands BzS(CH2)nSBz (n = 1-4) is not predictable. However, with more flexible spacer chains BzS(CH2)nSBz (n = 6-9), a clear structural pattern can be established. Using a 1:1 CuX-to-ligand ratio, [{Cu(µ2-X)2Cu}(µ-L4-7)2] CPs are always formed, irrespectively of L4-L7. Employing a 2:1 CuX-to-ligand ratio, only CuI is able to form networks incorporating Cu4(µ3-I)4 clusters as SBUs. All attempts to construct polynuclear cluster using CuBr and CuCl failed. The materials have been furthermore analyzed by powder X-ray diffraction, Raman spectroscopy, and thermogravimetric analysis, and the photophysical properties of the emissive materials have been studied.

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

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

Control of Structures and Emission Properties of (CuI) n 2-Methyldithiane Coordination Polymers.

A structurally unique and strongly luminescent nonporous 3D coordination polymer (CP) [Cu8I8(methyldithiane)4] n, CP3, has been prepared in a quasi-anticipated manner from 2-methyl-1,3-dithiane, L1, and CuI. This CP incorporates an unprecedented Cu8I8 cluster built upon two side-fused open cubanes. The crystal structure of CP3 has been determined at 100, 150, 200, 250, 300, 350, and 400 K to study the temperature dependence of the Cu···Cu distances. Two other topological 1D and 2D CPs isomers of formula [{Cu2I2}(L1)2] n featuring dinuclear {Cu2(µ2-I)2} rhomboids were also obtained independently by control of the reaction conditions. These two CPs convert into CP3 in hot PrCN, thus indicating that this latter material is the thermodynamic product. While CP1 and CP2 are not emissive, CP3 exhibits an intense luminescence due to the incorporation of the octanuclear Cu8I8 clusters as secondary building units within the network. The photophysical properties of CP3 have been investigated and rationalized by means of DFT and TDDFT computing. Furthermore, the thermal stability of these materials has been studied by ATG and DSC analyses. The Raman spectra of CP1-3 have been recorded in the solid state in the 50-500 cm-1 region.

Ferrocene-BODIPYmerocyanine dyads: new NIR absorbing platforms with optical properties susceptible to protonation.

Ferrocene-BODIPYmerocyanine dyads 5 and 6 were prepared and characterized by a variety of spectroscopic, electrochemical, and theoretical methods. Experimental and theoretical data on these NIR absorbing compounds are suggestive of unusual susceptibility (for BODIPY chromophores) of the delocalized π-system in 5 and 6 to protonation and low-potential oxidation of their π-systems.