The synthesis of new dinuclear complexes containing linked Ru-II(dppz) and Re-I(dppz) moieties is reported. The photophysical and biological properties of the new complex, which incorporates a N,N'-bis(4-pyridylmethyl)-1,6-hexanediamine tether ligand, are compared to a previously reported Ru-II/Re-I complex linked by a simple dipyridyl alkane ligand. Although both complexes bind to DNA with similar affinities, steady-state and time-resolved photophysical studies reveal that the nature of the linker affects the excited state dynamics of the complexes and their DNA photocleavage properties. Quantum-based DFT calculations on these systems offer insights into these effects. While both complexes are live cells permeant, their intracellular localizations are significantly affected by the nature of the linker. Notably, one of the complexes displayed concentration-dependent localization and possesses photophysical properties that are compatible with SIM and STED nanoscopy. This allowed the dynamics of its intracellular localization to be tracked at super resolutions.

The compounds 4,4'-dicyano-2,2'-bipyridyl (dcbpy), 4,4'-bis(4-cyanophenyl)-2,2'-bipyridyl (bcpbpy), 4,4'-bisRE)-2-(4-cyanophenyl)viny1]-2,2'-bipyridyl (bcpvbpy), and 4,4'-bis[(E)-2-(4-pyridyl)vinyl]-2,2'-bipyridyl (bpvbpy) are used to prepare nine new complexes with fac{ReI(CO)(3)(L)}(n+) (L = Cl-, pyridine (py), or 4-yanopyridine (cpy)) centers. The cationic complexes are isolated as their OTt- salts. These new monometallic species are studied together with the known fac-(ReCl)-Cl-I(CO)(3)(qpy) (qpy = 4,4':2',2 '':4 '',4'''-quaterpyridyl) (de Wolf, P.; et al. Inorg. Chim. Acta 2003, 355, 280-285). Coordination of {Ru-II(NH3)(5)}(2+)centers to the peripheral N atoms, of fac-(ReCl)-Cl-I(CO)(3)(qpy) and fac-[Re-I(CO)(3)(bcpbpy)(py)(+) affords heterotrimetallic complexes that are isolated as their PF6- alts. Single-crystal X-ray structures are reported for the solvates fac-(ReCl)-Cl-I(CO)(3)(dcbpy)center dot Me2CO, fac-[(ReCl)-Cl-I(CO)(3)(dcbpy) (MeCN)]OTf center dot PhMe, fac-[(ReCl)-Cl-I(CO)(3)(dcbpy) OTf center dot(dcbpy)(cpy)]OTIO.SMe2CO, fac-(ReCl)-Cl-I(CO)(3)(bcpbpy)-0.513hMe, and fac-[(ReCl)-Cl-I(CO)(3)(bcpbpy)(MeCN)OTf MeCN. Cyclic voltammetry reveals irreversible Re-II/I processes in all cases, while the trimetallic compounds show a reversible two-electron Ru-III/(II) oxidation wave. Ligand-based reductions are generally irreversible, but reversible waves are observed for the dcbpy complexes. Electronic absorption spectra show strong d -> pi* metal-to-ligand charge-transfer (MLCT) and intraligand pi -> pi* absorptions. The Ru-II-based MLCT bands have lower energies and higher intensities than the ReI-based ones. The monometallic species emit weakly in the red/NIR region (lambda(em) = 594-732 nm; phi = 0.6-8.1%) when excited at 350-520 nm. Molecular first hyperpolarizabilities beta for the trimetallic complex salts are measured in MeCN solutions via the hyper-Rayleigh scattering technique at 1064 nm. Stark (electroabsorption)_ spectroscopic studies on the low-energy MLCT bands in frozen PrCN allow the indirect, estimation of static first hyperpolarizabilities beta(0). The trimetallic complexes have relatively large beta(0) values, ca. 500 x 10(-30) esu or more, which are substantially greater than those of the monometallic species.

The compounds 4,4′-bis[(E)-2-R-vinyl]-2,2′-bipyridyl {R = ferrocenyl [(Fcv)2bpy], octamethylferrocenyl [(Me8Fcv)2bpy] or 4-(diphenylamino)phenyl [(Dapv)2bpy]} are used to prepare eight new complexes with ZnIICl2, ZnII(OAc)2, or fac-ReICl(CO)3 centers. The recently reported complex fac-ReICl(CO)3[(Dapv)2bpy] (Horvath, R. et al. Inorg. Chem. 2013, 52, 1304) is also studied. Electronic absorption spectra show intense d → π* metal-to-ligand charge-transfer (MLCT) and π → π* intraligand charge-transfer (ILCT) absorption bands, the relative energies of which correlate logically with the molecular structure. Cyclic voltammetry reveals a reversible oxidation wave for the Fc/Me8Fc complexes, accompanied by quasireversible or irreversible ligand-based reductions. The Re complexes also show irreversible ReII/I waves. Single-crystal X-ray structures are reported for (Me8Fcv)2bpy, ZnIICl2[(Me8Fcv)2bpy], ZnII(OAc)2[(Fcv)2bpy]·CHCl3, and fac-ReICl(CO)3[(Me8Fcv)2bpy]·0.5CHCl3. Molecular first hyperpolarizabilities β are measured in DCM solutions via the hyper-Rayleigh scattering (HRS) technique at 1300 nm. Stark (electroabsorption) spectroscopic studies on only the MLCT bands in frozen butyronitrile allow the indirect estimation of lower limits for the overall static first hyperpolarizabilities β0. Time-dependent density functional theory (TD-DFT) calculations on selected complexes confirm the expected assignments of their low energy absorption bands, with the best results obtained by using the M06 functional and Def2-TZVP/SVP/TZVPP mixed basis set. DFT predicts that the total static first hyperpolarizability βtot increases in the ZnIICl2 series in the order R = Fc < Me8Fc < Dap, consistent with the HRS and Stark data. The computed β values increase substantially on moving from the gas phase to a DCM or MeCN solvent medium, and the essentially 2D nature of the chromophores leads to dominant βxxy tensor components.

New complexes with six ferrocenyl (Fc) groups connected to Zn(II) or Cd(II) tris(2,2'-bipyridyl) cores are described. A thorough characterisation of their BPh4(-) salts includes two single-crystal X-ray structures, highly unusual for such species with multiple, extended substituents. Intense, visible d(Fe(II))→π* metal-to-ligand charge-transfer (MLCT) bands accompany the π→π* intraligand charge-transfer absorptions in the near UV region. Each complex shows a single, fully reversible Fe(III/II) wave when probed electrochemically. Molecular quadratic nonlinear optical (NLO) responses are determined by using hyper-Rayleigh scattering and Stark spectroscopy. The latter gives static first hyperpolarisabilities β0 reaching as high as approximately 10(-27)  esu and generally increasing with π-conjugation extension. Z-scan cubic NLO measurements reveal high two-photon absorption cross-sections σ2 of up to 5400 GM in one case. DFT calculations reproduce the π-conjugation dependence of β0, and TD-DFT predicts three transitions close in energy contributing to the MLCT bands. The lowest energy transition has octupolar character, whereas the other two are degenerate and dipolar in nature.

The copper(II) complexes [Cu(4)(1,3-tpbd)(2)(H(2)O)(4)(NO(3))(4)](n)(NO(3))(4n)·13nH(2)O (1), [Cu(4)(1,3-tpbd)(2)(AsO(4))(ClO(4))(3)(H(2)O)](ClO(4))(2)·2H(2)O·0.5CH(3)OH (2), [Cu(4)(1,3-tpbd)(2)(PO(4))(ClO(4))(3)(H(2)O)](ClO(4))(2)·2H(2)O·0.5CH(3)OH (3), [Cu(2)(1,3-tpbd){(PhO)(2)PO(2)}(2)](2)(ClO(4))(4) (4), and [Cu(2)(1,3-tpbd){(PhO)PO(3)}(2)(H(2)O)(0.69)(CH(3)CN)(0.31)](2)(BPh(4))(4)·Et(2)O·CH(3)CN (5) [1,3-tpbd = N,N,N',N'-tetrakis(2-pyridylmethyl)-1,3-benzenediamine, BPh(4)(-) = tetraphenylborate] were prepared and structurally characterized. Analyses of the magnetic data of 2, 3, 4, and [Cu(2)(2,6-tpcd)(H(2)O)Cl](ClO(4))(2) (6) [2,6-tpcd = 2,6-bis[bis(2-pyridylmethyl)amino]-p-cresolate] show the occurrence of weak antiferromagnetic interactions between the copper(II) ions, the bis-terdentate 1,3-tpbd/2,6-tpcd, μ(4)-XO(4) (X = As and P) μ(1,2)-OPO and μ-O(phenolate) appearing as poor mediators of exchange interactions in this series of compounds. Simple orbital symmetry considerations based on the structural knowledge account for the small magnitude of the magnetic couplings found in these copper(II) compounds.

Synthetic methods toward ruthenium(II) complexes incorporating the benzo[i]dipyrido[3,2-a:2',3'-c]phenazine-11,16-quinone ligand, qdppn, are reported. In several cases, it was found that complexes containing coordinated benzo[i]dipyrido[3,2-a:2',3'-c]phenazine, dppn, could be chemically or photochemically oxidized to their qdppn analogues. Since this method was not possible in all the cases, a new, higher yielding, convenient synthesis of qdppn was developed. The crystal structure of the complex [Ru(phen)(2)(qppn)](PF(6))(2) (phen = 1,10-phenanthroline) which was synthesized from free qdppn reveals that a combination of π-π stacking between coordinated phen and qdppn units, as well as anion-ligand hydrogen bonding, define large hexagonal channels which are occupied by anions and solvent molecules. Electrochemical and photophysical studies reveal that the new qdppn-based complexes are not luminescent and, in contrast to their dppn analogues, they are also poor singlet oxygen sensitizers. Time-resolved studies and density functional theory (DFT) calculations indicate that optical properties of the new complexes are due to a short-lived charge separated state involving the quinone moiety of qdppn. The DNA binding properties of the new complexes have also been investigated. It was found that they are intercalators, displaying binding affinities which are comparable to their dppn analogues.

The zinc complexes [(L1)(2)Zn(MeOH)(2)](OTf)(2), [(L1)ZnCl(2)], [(L2)ZnCl(2)], [(L2)Zn(OTf)(H(2)O)]OTf and [(Me-bispic)ZnCl(2)] of the ligands N-[(2-pyridyl)methyl]-2,2'-dipyridylamine (L1), N-[bis(2-pyridyl)methyl]-2-pyridylamine (L2) and N-methyl-[bis(2-pyridyl)methyl]amine (Me-bispic) were synthesised and characterised. The first copper(I) complexes of the ligands L1 and L2 were also synthesised and structurally characterised. [(L1)ZnCl(2)] showed unexpected fluxional behaviour in solution and revealed an interesting intramolecular ligand exchange mechanism in the coordination sphere of the zinc ion. Furthermore, strong blue emission was observed under UV-light excitation.

Four new dipolar cations have been synthesized, containing ferrocenyl electron donor groups and diquaternized 2,2'-bipyridyl (diquat) acceptors. To our knowledge, these are the first organometallic diquat derivatives to be reported and have been characterized as their PF6- salts by using various techniques including H-1 NMR and electronic absorption spectroscopies and cyclic voltammetry. UV-vis spectra show multiple intramolecular charge-transfer bands, and three reversible redox processes are observed for each compound. Molecular quadratic nonlinear optical (NLO) responses have been determined by using hyper-Rayleigh scattering at 1064 nm and Stark (electroabsorption) spectroscopic studies on the intense pi ->pi* intraligand and d ->pi* metal-to-ligand charge-transfer bands. The most active compounds have estimated, Stark-derived beta(0) values approaching that of the chromophore in the technologically important material (E)-4'-(dimethylamino)-N-methyl-4-stilbazolium tosylate. Single-crystal X-ray structures have been obtained for three of the salts, with one adopting the orthorhombic space group Aba2 and having potential for bulk NLO behavior due to its polar structure. Attempted crystallizations of the remaining chromophore revealed that it undergoes an unusual intermolecular formal Michael cycloaddition between an activated methyl group and a double bond, forming a dimeric species. This diastereomeric cyclic complex has also been characterized via single-crystal X-ray diffraction.

In this article, we describe a series of complexes with electron-rich cis-{Ru-II(NH3)(4)}(2+) centers coordinated to two pyridyl ligands bearing N-methyl/arylpyridinium electron-acceptor groups. These V-shaped dipolar species are new, extended members of a class of chromophores first reported by us (Coe, B. J. et al. J. Am. Chem. Soc. 2005, 127,4845-4859). They have been isolated as their PF6- salts and characterized by using various techniques including H-1 NMR and electronic absorption spectroscopies and cyclic voltammetry. Reversible Ru-III/II waves show that the new complexes are potentially redox-switchable chromophores. Single crystal X-ray structures have been obtained for four complex salts; three of these crystallize noncentrosymmetrically, but with the individual molecular dipoles aligned largely antiparallel. Very large molecular first hyperpolarizabilities beta have been determined by using hyper-Rayleigh scattering (HRS) with an 800 nm laser and also via Stark (electroabsorption) spectroscopic studies on the intense, visible d -> pi* metal-to-ligand charge-transfer (MLCT) and pi -> pi* intraligand charge-transfer (ILCT) bands. The latter measurements afford total nonresonant beta(0) responses as high as ca. 600 x 10(-30) esu. These pseudo-C-2v chromophores show two substantial components of the beta tensor, beta(zzz) and beta(zyy), although the relative significance of these varies with the physical method applied. According to HRS, beta(zzz) dominates in all cases, whereas the Stark analyses indicate that beta(zyy) is dominant in the shorter chromophores, but beta(zzz) and beta(zyy) are similar for the extended species. In contrast, finite field calculations predict that beta(zyy) is always the major component. Time-dependent density functional theory calculations predict increasing ILCT character for the nominally MLCT transitions and accompanying blue-shifts of the visible absorptions, as the ligand;pi-systems are extended. Such unusual behavior has also been observed with related 1D complexes (Coe, B. J. et al. J. Am. Chem. Soc. 2004, 126, 3880-3891).

In this article, we present a detailed study of structure-activity relationships in diquaternized 2,2'-bipyridyl (diquat) derivatives. Sixteen new chromophores have been synthesized, with variations in the amino electron donor substituents, pi-conjugated bridge, and alkyl diquaternizing unit. Our aim is to combine very large, two-dimensional (2D) quadratic nonlinear optical (NLO) responses with reversible redox chemistry. The chromophores have been characterized as their PF(6)(-) salts by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. Their visible absorption spectra are dominated by intense pi --> pi* intramolecular charge-transfer (ICT) bands, and all show two reversible diquat-based reductions. First hyperpolarizabilities beta have been measured by using hyper-Rayleigh scattering with an 800 nm laser, and Stark spectroscopy of the ICT bands affords estimated static first hyperpolarizabilities beta(0). The directly and indirectly derived beta values are large and increase with the extent of pi-conjugation and electron donor strength. Extending the quaternizing alkyl linkage always increases the ICT energy and decreases the E(1/2) values for diquat reduction, but a compensating increase in the ICT intensity prevents significant decreases in Stark-based beta(0) responses. Nine single-crystal X-ray structures have also been obtained. Time-dependent density functional theory clarifies the molecular electronic/optical properties, and finite field calculations agree with polarized HRS data in that the NLO responses of the disubstituted species are dominated by 'off-diagonal' beta(zyy) components. The most significant findings of these studies are: (i) beta(0) values as much as 6 times that of the chromophore in the technologically important material (E)-4'-(dimethylamino)-N-methyl-4-stilbazolium tosylate; (ii) reversible electrochemistry that offers potential for redox-switching of optical properties over multiple states; (iii) strongly 2D NLO responses that may be exploited for novel practical applications; (iv) a new polar material, suitable for bulk NLO behavior.

We describe a series of nine new complex salts in which electron-rich Ru-II or Fe-II centers are connected via pi-conjugated bridges to six electron-accepting N-methyl-/N-arylpyridinium groups. This work builds upon our previous preliminary studies (Coe, B. J. J. Am. Chem. Soc. 2005, 127, 13399-13410; J. Phys. Chem. A 2007, 111, 472-478), with the aims of achieving greatly enhanced NLO properties and also combining large quadratic and cubic effects in potentially redox-switchable molecules. Characterization has involved various techniques, including electronic absorption spectroscopy and cyclic voltammetry. The complexes display intense, visible d -> pi* metal-to-ligand charge-transfer (MLCT) bands, and their pi ->pi* intraligand charge-transfer (ILCT) absorptions in the near-UV region show molar extinction coefficients as high as ca. 3.5 x 10(5) M-1 cm(-1). Molecular quadratic nonlinear optical (NLO) responses beta have been determined by using hyper-Rayleigh scattering at 800 and 1064 nm and also via Stark (electroabsorption) spectroscopic studies. The directly and indirectly derived beta values are very large, with the Stark-based static first hyperpolarizabilities beta(0) reaching as high as ca. 10(-27) esu, and generally increase on extending the pi-conjugation and enhancing the electron-accepting strength of the ligands. Cubic NLO properties have also been measured by using the Z-scan technique, revealing relatively high two-photon absorption cross sections of up to 2500 GM at 750 nm.

Six new dicationic 2D nonlinear optical (NLO) chromophores with pyrazinyl-pyridinium electron acceptors have been synthesized by nucleophilic substitutions of 2,6-dichloropyrazine with pyridyl derivatives. These compounds have been characterized as their PF(6)(-) salts by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. Large red shifts in the intense, π → π* intramolecular charge-transfer (ICT) transitions on replacing -OMe with -NMe(2) substituents arise from the stronger π-electron donor ability of the latter. Each compound shows a number of redox processes which are largely irreversible. Single crystal X-ray structures have been determined for five salts, including two nitrates, all of which adopt centrosymmetric packing arrangements. Molecular first hyperpolarizabilities β have been determined by using femtosecond hyper-Rayleigh scattering at 880 and 800 nm, and depolarization studies show that the NLO responses of the symmetric species are strongly 2D, with dominant "off-diagonal" β(zyy) components. Stark (electroabsorption) spectroscopic measurements on the ICT bands afford estimated static first hyperpolarizabilities β(0). The directly and indirectly derived β values are large, and the Stark-derived β(0) response for one of the new salts is several times greater than that determined for (E)-4'-(dimethylamino)-N-methyl-4-stilbazolium hexafluorophosphate. These Stark spectroscopic studies also permit quantitative comparisons with related 2D, binuclear Ru(II) ammine complex salts.

Six new nonlinear optical (NLO) chromophores with pyrazinyl-pyridinium electron acceptors have been synthesized by complexing a known pro-ligand with electron donating {Ru(II)(NH(3))(5)}(2+) or trans-{Ru(II)(NH(3))(4)(py)}(2+) (py = pyridine) centers. These cationic complexes have been characterized as their PF(6)(-) salts by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. The visible d → π* metal-to-ligand charge-transfer (MLCT) absorptions gain intensity on increasing the number of Ru(II) centers from one to two, but remain at constant energy. One or two Ru(III/II) redox processes are observed which are reversible, quasi-reversible, or irreversible, while all of the ligand-based reductions are irreversible. Molecular first hyperpolarizabilities β have been determined by using hyper-Rayleigh scattering (HRS) at 1064 nm, and depolarization studies show that the NLO responses of the symmetric species are strongly two-dimensional (2D) in character, with dominant "off-diagonal" β(zyy) components. Stark (electroabsorption) spectroscopic measurements on the MLCT bands also allow the indirect determination of estimated static first hyperpolarizabilities β(0). Both the HRS and the Stark-derived β(0) values increase on moving from mono- to bimetallic complexes, and substantial enhancements in NLO response are achieved when compared with one-dimensional (1D) and 2D monometallic Ru(II) ammine complexes reported previously.

A series of chromophoric salts has been prepared in which 4-(diphenylamino)phenyl (Dpap) electron donor groups are connected to electron-accepting diquaternized 2,2'-bipyridyl (diquat) units. The main aim is to combine large quadratic and cubic nonlinear optical (NLO) effects in potentially redox-switchable molecules with 2D structures. The chromophores have been characterized as their PF(6)(-) salts by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. The visible absorption spectra are dominated by intense π → π* intramolecular charge-transfer (ICT) bands, and all of the compounds show two reversible or quasireversible diquat-based reductions and partially reversible Dpap oxidations. Single crystal X-ray structures have been obtained for one salt and for the precursor compound (E)-4-(diphenylamino)cinnamaldehyde, both of which adopt centrosymmetric space groups. First hyperpolarizabilities β have been measured by using hyper-Rayleigh scattering (HRS) with a 800 nm laser, and Stark (electroabsorption) spectroscopy of the ICT bands affords estimated static first hyperpolarizabilities β(0). The directly and indirectly derived β values are large and generally increased substantially for the bis-Dpap derivatives when compared with their monosubstituted analogues. Polarized HRS studies show that the NLO responses of the disubstituted species are dominated by "off-diagonal" β(zyy) components. Lengthening the diquaternizing alkyl unit lowers the electron-acceptor strength and therefore increases the ICT energies and decreases the E(1/2) values for diquat reduction. However, compensating increases in the ICT intensity prevent significant decreases in the Stark-based β(0) responses. Cubic NLO properties have been measured by using the Z-scan technique over a wavelength range of 520-1600 nm, revealing relatively high two-photon absorption cross-sections of up to 730 GM at 620 nm for one of the disubstituted chromophores.

The photophysical properties of a series of Ru(II) complexes containing benzo[i]dipyrido[3,2-a:2',3'-c]phenazine (dppn) as a ligand are reported. Transient absorption spectroscopy studies indicate that, in contrast to related Ru(dppz) complexes (dppz = dipyrido[3,2-a:2',3'-c]phenazine), the excited state of all the dppn systems is a long-lived pipi* triplet state. Computational studies (DFT and TD-DFT) confirm that the excited state is based on the dppn ligand. Near-infrared luminescence studies reveal that the complexes are efficient singlet oxygen sensitizers with yields of 70-83%.

Three new complex salts Na(2)[Fe(II)(CN)(5)(L)] [L = N-methyl-4-{E,E-4-(4-pyridyl)buta-1,3-dienyl}pyridinium, N-methyl-4-{E,E,E-6-(4-pyridyl)hexa-1,3,5-trienyl}pyridinium, or N-methyl-1,4-bis-{E-2-(4-pyridyl)ethenyl}] benzene have been prepared. These compounds have been characterized by using various techniques including electronic absorption spectroscopy and cyclic voltammetry, allowing their properties to be compared with those of the known complexes where L = N-methylpyrazinium (Mepyz(+)), N-methyl-4,4'-bipyridinium, or N-methyl-4-[E-2-(4-pyridyl)ethenyl]pyridinium. Molecular quadratic nonlinear optical (NLO) responses have been determined by using hyper-Rayleigh scattering (HRS) at 1064 nm, and also via Stark (electroabsorption) spectroscopic studies on the intense, visible d --> pi* metal-to-ligand charge-transfer (MLCT) bands. The MLCT transitions show large red-shifts on moving from aqueous to methanol solutions, and these excitations are associated with relatively large static first hyperpolarizabilities beta(0). Single crystal X-ray structures of two hydrated materials containing the complex anion [Fe(II)(CN)(5)(Mepyz(+))](2-) have been determined, and both of these show some degree of alignment of the constituent complex dipoles.

A series of five new dipolar cations hits been synthesized with ferrocenyl (Fc) electron donor groups connected to N-arylpyridinium, N-methylquinolinium, N-methylbenzothiazolium, or N-methylacridinium acceptors. Together with their known N-methylpyridinium analogue, these chromophores have been characterized as their PF6- salts by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. Nine single-crystal X-ray structures have been determined, including two polymorphs of one salt obtained from it single crystallization experiment, and two of these are polar materials. A highly favorable degree of dipolar alignment for bulk NLO effects is observed in one case. Molecular quadratic nonlinear optical (NLO) responses have been determined by using femtosecond hyper-Rayleigh scattering (HRS) at 1300 rim and also via Stark (electroabsorption) spectroscopic studies oil the intense pi -> pi* intraligand and d -> pi* metal-to-ligand charge-transfer bands. A broad correlation between the electron acceptor strength and the HRS-derived first hyperpolarizabilities beta and the static first hyperpolarizabilities beta(0) estimated from the Stark data is evident. This is the first time that meaningful (albeit indirectly determined) beta(0) data have been reported for Fc compounds, allowing quantitative comparisons with the chromophore in the technologically important material (E)-4'-(dimethylamino)-N-methyl-4-stilbazolium (DAS) tosylate. The observed beta(0) values are in several cases similar to that of [DAS]PF6, and possibly even larger in one instance.

Twelve, dipolar cations with 2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-9-yl (julolidinyl, Jd) electron donor groups and N-methyl/arylpyridinium, N-methylquinolinium or N-methylbenzothiazolium acceptor groups were synthesised. The chromophores were characterised as their PF6− salts using various techniques including electronic absorption spectroscopy and cyclic voltammetry; single crystal X-ray structures were determined for a large number of salts, all of which form nonpolar materials. A broad correlation between the electron acceptor strength and the degree of bond length alternation is evident. A key focus of this work is detailed comparisons of the Jd-containing chromophores with their previously studied 4-(dimethylamino)phenyl (Dap) analogues. Molecular, quadratic, nonlinear optical responses were determined using femtosecond hyper-Rayleigh scattering at both 1300 and 800nm, as well as using Stark (electroabsorption) spectroscopic studies of intense, visible π→π∗ intramolecular charge-transfer bands. Substantial red shifts in the latter transitions are observed on replacing Dap with Jd which indicate that the latter acts as a more effective π-electron donor. With few exceptions, both hyper-Rayleigh scattering and Stark data generally show that using Jd instead of Dap increases the static first hyperpolarizability β0, in accord with expectations based on the two-state model. β0 values as high as 6 times larger than that of the chromophore in the technologically important material E-4′-(dimethylamino)-N-methyl-4-stilbazolium tosylate are observed.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Ein DNA-Multifunktionswerkzeug: In photo- und biophysikalischen Studien erwies sich der abgebildete Heterozweikernkomplex [{Ru(tpm)(dppz)}(μ-dpp[5]){fac-(CO)3Re(dppz)}]3+ sowohl als DNA-„Lichtschalter“ als auch als direktes Spaltungsagens; tpm=Tris(1-pyrazolyl)methan; dppz=Dipyrido[3,2-a:2′,3′-c]phenazin; dpp[5]=4,4′-Dipyridylpentan.