Sub-Doppler rotationally resolved spectroscopy of lower vibronic bands of benzene with Zeeman effects

Sub-Doppler high-resolution excitation spectra and the Zeeman effects of the 6(0)(1), 1(0)(1)6(0)(1), and 1(0)(2)6(0)(1) bands of the S1(1)B2u<--S(0)(1)A1g transition of benzene were measured by crossing laser beam perpendicular to a collimated molecular beam. 1593 rotational lines of the 1(0) (1)6(0) (1) band and 928 lines of the 1(0)(2)6(0)(1) band were assigned, and the molecular constants of the excited states were determined. Energy shifts were observed for the S1(1)B2u(v1=1,v6=1,J,Kl=-11) levels, and those were identified as originating from a perpendicular Coriolis interaction. Many energy shifts were observed for the S1(1)B2u(v1=2,v6=1,J,Kl) levels. The Zeeman splitting of a given J level was observed to increase with K and reach the maximum at K=J, which demonstrates that the magnetic moment lies perpendicular to the molecular plane. The Zeeman splittings of the K=J levels were observed to increase linearly with J. From the analysis, the magnetic moment is shown to be originating mostly from mixing of the S1(1)B2u and S2(1)B1u states by the J-L coupling (electronic Coriolis interaction). The number of perturbations was observed to increase as the excess energy increases, and all the perturbing levels were found to be a singlet state from the Zeeman spectra.     

Dual electron transfer pathways from 4,4'-dimethoxybenzophenone ketyl radical in the excited state to parent molecule in the ground state

Dual intermolecular electron transfer (ELT) pathways from 4,4'-dimethoxybenzophenone (1) ketyl radical (1H*) in the excited state [1H*(D1)] to the ground-state 4,4'-dimethoxybenzophenone [1(S0)] were found in 2-methyltetrahydrofuran (MTHF) by observing bis(4-methoxyphenyl)methanol cation (1H+) and 4,4'-dimethoxybenzophenone radical anion (1*-) during nanosecond-picosecond two-color two-laser flash photolysis. ELT pathway I involved the two-photon ionization of 1H* following the injection of electron to the solvent. The solvated electron was quickly trapped by 1(S0) to produce 1*-. ELT pathway II was a self-quenching-like ELT from 1H*(D1) to 1(S0) to give 1H+ and 1*-. From the fluorescence quenching of 1H*(D1), the ELT rate constant was determined to be 1.0 x 10(10) M(-1) s(-1), which is close to the diffusion-controlled rate constant of MTHF. The self-quenching-like ELT mechanism was discussed on the basis of Marcus' ELT theory.     

Head-to-head vinyl polymers. IV. Preparation and characterization of equimolar head-to-head copolymers of acrylic acid and its esters

The alternating copolymer of ethylene with maleic anhydride was esterified with a number of aliphatic alcohols to yield its monoesters, which correspond structurally to equimolar (1:1) head-to-head (h-h) copolymers of acrylic acid with alkyl acrylates. In addition, they were methylated with diazomethane to 1:1 h-h copolymers of methyl acrylate with alkyl acrylates. For comparison the 1:1 head-to-tail (h-t) copolymers of methyl acrylate with alkyl acrylates were prepared by radical copolymerizations. Some chemical, physical, and thermal properties of these 1:1 h-h and h-t copolymers were evaluated and compared. The softening and glass transition temperatures of the 1:1 h-h copolymers were somewhat higher than those of the corresponding 1:1 h-t copolymers, which indicated that the h-h replacements made the polymer chain stiffer and less flexible. The 1:1 h-h copolymers were also observed to degrade thermally at somewhat higher temperatures and with higher rates than the 1:1 h-t copolymers. The ratio of alcohol to monomer found in the pyrolysis products was higher for the 1:1 h-h than for its respective 1:1 h-t copolymer.     

Sensitivity of (1)J[C(1)-H(1)] magnitudes to anomeric stereochemistry in 2,3-anhydro-O-furanosides.

The magnitude of the one-bond coupling constant between C(1) and H(1) in 2,3-anhydro-O-furanosides has been shown to be sensitive to the stereochemistry at the anomeric center. A panel of 24 compounds was studied and in cases where the anomeric hydrogen is trans to the epoxide moiety, (1)J[C(1)-H(1)] = 163-168 Hz; and when this hydrogen is cis to the oxirane ring, ((1)J[C(1)-H(1)] = 171-174 Hz. In contrast, for 2,3-anhydro-S-glycosides, the size of the (1)J[C(1)-H(1)] is not sensitive to C(1) stereochemistry. Computational studies on all four methyl 2,3-anhydro-O-furanosides (5-8) demonstrated that (1)J[C(1)-H(1)] was inversely proportional to the length of the C(1)-H(1) bond. A previously reported equation, which relates C(1)-H(1) bond distance and atomic charges to (1)J[C(1)-H(1)] magnitudes, could be used to accurately predict the J values in the alpha-lyxo (5) and beta-ribo (8) isomers. In contrast, with the beta-lyxo (6) and alpha-ribo isomers (7), this equation underestimated the size of these coupling constants by 10-20 Hz.     

Conformational polymorphism of solid tetramesityldisilene Mes2Si=SiMes2 (Raman,UV-vis,IR and fluorescence study)

Conformational polymorphism of solid tetramesityldisilene (1) has been studied by the methods of optical spectroscopy. The three known modifications of 1: orange unsolvated 1a and two 1:1 solvates with toluene (1b) and THF (1c) have been found to transform under specific conditions to a new, most thermodynamically stable polymorph, yellow unsolvated powder 1d. The latter has been characterized by the Raman, IR, UV-vis and fluorescence data. All forms of 1 exhibit Raman spectra differing in details, which reflect their different crystal and molecular structures. Unsolvated 1a and 1d differ significantly in electronic absorption and fluorescence emission. The yellow form 1d can be converted to the orange form 1a upon illumination with laser light in the region 514-457 nm. Similarity of the Raman and UV-vis spectra of 1d to those of the solutions of 1 provides some evidence for a quasi-trans conformation of 1d.     

1-Phenyl-1-halo-1-silacyclohexanes

The approaches to synthesis of 1-phenyl-1-halo-1-silacyclohexanes C₅H₁₀Si(Ph)X (X = F, Cl, Br) have been examined. 1-Phenyl-1-chloro-1-silacyclohexane has been prepared via the known reaction of phenyltrichlorosilane with dimagnesium derivative of 1,5-dibromopentane; up to 20% of 1-bromo-1-phenyl-1-silacyclohexane admixture is formed along with the target product. The minor product formation has been prevented using an alternative method of chlorination of 1-phenyl-1-silacyclohexane with N-chlorosuccinimide. 1-Phenyl-1-fluoro-1-silacyclohexane has been obtained in close to quantitative yield via the reaction of 1-phenyl-1-chloro-1-silacyclohexane with SbF₃ and in 70% yield via its reaction with HF. The synthesis of 1-phenyl-1-bromo-1-silacyclohexane via bromination of 1-phenyl-1-chloro-1-silacyclohexane with N-bromosuccinimide has given the target product as a minor one, the major product being disiloxane formed due to hydrolysis of the Si–Br bond.     

New processes for the selective production of 1-octene

Linear α-olefins, especially 1-hexene and 1-octene, are key components for the production of LLDPE and the demand for 1-hexene and 1-octene increased enormously in recent years. To meet this demand several processes were developed in the last decade to produce 1-hexene and 1-octene selectively. Here we review the new processes for 1-octene production based on homogeneous catalysts.Sasol's coal-based high temperature Fischer–Tropsch technology produces an Anderson–Schulz–Flory distribution of hydrocarbons with high α-olefin content and the desired alkenes, including 1-heptene and 1-octene, are separated by distillation. In this case, as in the SHOP process, 1-octene constitutes only a minor part of the total yield.Nowadays other technologies are being applied or considered for on-purpose 1-octene production: hydroformylation of 1-heptene, the telomerization of 1,3-butadiene, and ethene tetramerization.1-Heptene can be converted in three steps to 1-octene: (1) hydroformylation of 1-heptene to octanal, (2) hydrogenation of octanal to 1-octanol, and (3) dehydration of 1-octanol to 1-octene. This process was commercialized by Sasol.Dow commercialized a process based on butadiene. Telomerization of butadiene with methanol in the presence of a palladium catalyst yields 1-methoxy-2,7-octadiene, which is fully hydrogenated to 1-methoxyoctane in the next step. Subsequent cracking of 1-methoxyoctane gives 1-octene and methanol for recycle. Recently highly active and stable phosphine based systems were reported that show particularly good performance for the industrially attractive feedstock, the C₄ cut of the paraffin cracker.1-Hexene can be obtained by ethene trimerization by a family of catalysts based mainly on Cr. High selectivity to 1-hexene can be achieved thanks the propensity of the chromium based catalyst to form 7-membered ring metallacycles. Sasol has found catalyst systems that allow the formation of a 9-membered metallacycle in large proportion relative to 7-membered ring formation, yielding 1-octene.     

Benchmarking the accuracy of coverage-dependent models: adsorption and desorption of benzene on Pt (1 1 1) and Pt3Sn (1 1 1) from first principles

Bimetallic catalysts have demonstrated properties favorable for upgrading biofuel through catalytic hydrodeoxygenation. However, the design and optimization of such bimetallic catalysts requires the ability to construct accurate, predictive models of these systems. To generate a model that predicts the kinetic behavior of benzene adsorbed on Pt (1 1 1) and a Pt₃Sn (1 1 1) surface alloy (Pt₃Sn (1 1 1)), the adsorption of benzene was studied for a wide range of benzene coverages on both surfaces using density functional theory (DFT) calculations. The adsorption energy of benzene was found to correlate linearly with benzene coverage on Pt (1 1 1) and Pt₃Sn (1 1 1); both surfaces exhibited net repulsive lateral interactions. Through an analysis of the d-band properties of the metal surface, it was determined that the coverage dependence is a consequence of the electronic interactions between benzene and the surface. The linear coverage dependence of the adsorption energy allowed us to quantify the influence of the lateral interactions on the heat of adsorption and temperature programmed desorption (TPD) spectra using a mean-field model. A comparison of our simulated TPD to experiment showed that this mean-field model adequately reproduces the desorption behavior of benzene on Pt (1 1 1) and Pt₃Sn (1 1 1). In particular, the TPD correctly exhibits a broadening desorption peak as the initial coverage of benzene increases on Pt (1 1 1) and a low temperature desorption peak on Pt₃Sn (1 1 1). However, due to the sensitivity of the TPD peak temperature to the desorption energy, precise alignment of experimental and theoretical TPD spectra demands an accurate calculation of the adsorption energy. Therefore, an analysis of the effect of the exchange-correlation functional on TPD modeling is presented. Through this work, we show the necessity of incorporating lateral interactions into theoretical models in order to correctly predict experimental behavior.     

Kinetics of surface modification induced by submonolayer electrochemical oxygen adsorption on Pt(1 1 1)

Electrochemical oxygen adsorption/desorption below monolayer level leads to a disordering of platinum single-crystal surfaces vicinal to the (1 1 1) plane. The kinetics can be described by means of a consecutive reaction from (1 1 1)-terrace sites to (1 1 0)-defect sites, in which (1 0 0)-defects act as intermediates. The first oxidation of the electrode reflects independent contributions from terrace and step sites, the latter being structure sensitive. Oxygen adsorption charges amount to a mean value of one electron per step site.     

A mechanistic insight into caspase-7 inhibition by BIR1-2 domains of XIAP and cIAP1

Previous studies failed to demonstrate any role for the BIR1 domain of the inhibitor of apoptosis proteins (IAPs) in inhibition of executioner caspases. In this study, XIAP-BIR1-2 and c-IAP1-BIR1-2 domains have been used to investigate the role of BIR1 in the inhibition of caspase-7. Kinetic analysis confirmed that caspase-7 was inhibited in an uncompetitive manner at lower concentrations of XIAP-BIR1-2, whereas the inhibition was switched to the mixed type mode at higher concentrations of the inhibitor. In contrast, cIAP1-BIR1-2 inhibited caspase-7 in a mixed type mode at all examined concentrations. These data suggest that the presence of BIR1 is essential for inhibition of caspase-7 by cIAP1. Far-UV CD and fluorescence spectroscopy experiments showed that despite similar secondary structures, XIAP-BIR1-2 and cIAP1-BIR1-2 have different biophysical properties. BIR1-2 domain of XIAP was found to be more flexible than cIAP1, which may be the reason behind differences in their kinetic properties.     

Structural signature of the MYPT1-PP1 interaction

Muscle relaxation is triggered by the dephosphorylation of Ser19 in the myosin regulatory light chain. This reaction is catalyzed by the holoenzyme myosin phosphatase (MP), which includes the catalytic subunit protein phosphatase 1 (PP1) and the regulatory targeting subunit (MYPT). MYPT1 (myosin phosphatase targeting subunit 1) is responsible for both targeting the holoenzyme to subcellular compartments in the muscle and directing PP1 specificity toward myosin. To understand the molecular events leading to the MYPT1-PP1 holoenzyme formation, we used NMR spectroscopy to determine the structural and dynamic characteristics of unbound MYPT1. This allowed the conformations of MYPT1 in the free, unbound state to be directly compared to the PP1-bound state. Our results show that MYPT1(1-98) behaves like a two-domain protein in solution. The first 40 residues of MYPT1(1-98), the disordered region, are intrinsically disordered and highly dynamic, whereas residues 41-98, the folded ankyrin-repeat region, are well-structured and rigid. Furthermore, the integrated use of NMR and biophysical data enabled us to calculate an ensemble model for MYPT1(1-98). The most prominent structural feature of the MYPT1(1-98) ensemble is a 25% populated transient α-helix in the disordered region of MYPT1(1-98). This α-helix becomes fully populated when bound to PP1 and, as we show, likely plays a central role in the formation of the MYPT1-PP1 holoenzyme complex. Finally, this combined analysis shows that the structural and dynamic behaviors exhibited by MYPT1 for PP1 are distinct from those of any other previously analyzed PP1 regulatory protein. Collectively, these data enable us to present a new model of the molecular events that drive MYPT1-PP1 holoenzyme formation and demonstrate that there are structural differences in unbound PP1 regulators that have not been previously observed. Thus, this work adds significant insights to the currently limited data for molecular structures and dynamics of PP1 regulators.     

Nickel oxidation states of F(430) cofactor in methyl-coenzyme M reductase

Magnetic circular dichroism (MCD) spectroscopy and variable-temperature variable-field MCD are used in combination with density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations to characterize the so-called ox1-silent, red1, and ox1 forms of the Ni-containing cofactor F430 in methyl-coenzyme M reductase (MCR). Previous studies concluded that the ox1 state, which is the precursor of the key reactive red1 state of MCR, is a Ni(I) species that derives from one-electron reduction of the Ni(II)-containing ox1-silent state. However, our absorption and MCD data provide compelling evidence that ox1 is actually a Ni(II) species. In support of this proposal, our DFT and TD-DFT calculations indicate that addition of an electron to the ox1-silent state leads to formation of a hydrocorphin anion radical rather than a Ni(I) center. These results and biochemical evidence suggest that ox1 is more oxidized than red1, which prompted us to test a new model for ox1 in which the ox1-silent species is oxidized by one electron to form a thiyl radical derived from coenzyme M that couples antiferromagnetically to the Ni(II) ion. This alternative ox1 model, formally corresponding to a Ni(III)/thiolate resonance form but with predicted S = 1/2 EPR parameters reminiscent of a Ni(I) (3dx2-y2)1 species, rationalizes the requirement for reduction of ox1 to yield the red1 species and the seemingly incongruent EPR and electronic spectra of the ox1 state.     

Contrasting singlet-triplet dynamical behavior of two vibrational levels of the acetylene S1 2(1)3(1)B2 polyad

Surface electron ejection by laser-excited metastables (SEELEM) and LIF spectra of acetylene were simultaneously recorded in the regions of the A1Au-X1Sigmag+ nominal 2(1)3(1)4(2) Ka=1<--00 and 2(1)3(1)6(2) Ka=1<--00 bands near 46,140 cm(-1). The upper states of these two bands are separated by only approximately 100 cm(-1), and the two S1 vibrational levels are known to be strongly mixed by anharmonic and Coriolis interactions. Strikingly different patterns were observed in the SEELEM spectra in the regions of the 2(1)3(1)4(2) and 2(1)3(1)6(2) vibrational levels. Because the equilibrium structure of the T3 electronic state is known to be nonplanar, excitation of nu4 (torsion) and nu6 (antisymmetric in-plane bend) are expected respectively to promote and suppress vibrational overlap between low-lying S1 and T3 vibrational levels. The nearly 50:50 mixed 2(1)3(1)4(2)-2(1)3(1)6(2) character of the S1 vibrational levels rules out this simple Franck-Condon explanation for the different appearance of the SEELEM spectra. A simple model is applied to the SEELEM/LIF spectra to explain the differences between spectral patterns in terms of a T3 doorway-mediated singlet-triplet coupling model.     

Ab initio study on deactivation pathways of excited 9H-guanine

The complete active space with second-order perturbation theory/complete active space self-consistent-field method was used to explore the nonradiative decay mechanism for excited 9H-guanine. On the 1pipi* (1L(a)) surface we determined a conical intersection (CI), labeled (S0pipi*)(CI), between the 1pipi* (1L(a)) excited state and the ground state, and a minimum, labeled (pipi*)min. For the 1pipi* (1L(a)) state, its probable deactivation path is to undergo a spontaneous relaxation to (pipi*)min first and then decay to the ground state through (S0pipi*)(CI), during which a small activation energy is required. On the 1n(N)pi* surface a CI between the 1n(N)pi* and 1pipi* (1L(a)) states was located, which suggests that the 1n(N)pi* excited state could transform to the 1pipi* (1L(a)) excited state first and then follow the deactivation path of the 1pipi* (1L(a)) state. This CI was also possibly involved in the nonradiative decay path of the second lowest 1pipi* (1L(b)) state. On the 1n(O)pi* surface a minimum was determined. The deactivation of the 1n(O)pi* state to the ground state was estimated to be energetically unfavorable. On the 1pisigma* surface, the dissociation of the N-H bond of the six-membered ring is difficult to occur due to a significant barrier.     

1H-1H dipolar couplings provide a unique probe of RNA backbone structure

A NMR method is described that permits simultaneous measurement of the geminal 2JH1H2 + 2DH1H2 splitting and the sum of the 1JCH1 + 1DCH1 + 1JCH2 + 1DCH2 couplings for methylene groups, where 2DH1H2 and 1DCH are residual dipolar couplings, occurring when molecules are weakly oriented relative to the magnetic field. By suppressing either the upfield or downfield half of the 1H-1H geminal doublet, the experiment yields improved resolution relative to regular two-dimensional 1H-13C correlation spectra, making it applicable to systems of considerable complexity. The method is demonstrated for measurement of all 2DH5'H5' couplings in a 24-nucleotide 13C-enriched RNA stem loop structure, weakly aligned in liquid crystalline Pf1. The method is equally applicable to methylene groups in 13C-labeled proteins and to natural abundance samples of smaller molecules.     

Regio- and stereoisomeric control of the aggregation of zinc-chlorins possessing inverted interactive hydroxyl and carbonyl groups.

As models for a self-aggregative, naturally occurring magnesium-chlorin bacteriochlorophyll-d possessing 3(1)-secondary alcoholic hydroxyl and 13(1)-oxo groups, zinc-chlorins were synthesized with 3(1)-oxo and 13(1)-secondary (1) or tertiary hydroxyl groups (2). Compared to the monomers in a tetrahydrofuran solution, diastereomers 13(1)R-1R and 13(1)S-1S gave red-shifted absorption maxima (643 --> 674 nm in 1R and 708 nm in 1S) in 1 v/v% CH(2)Cl(2)-hexane solution, indicating their self-aggregation. Therefore, the positioning of the two groups at 3(1)/13(1) or 13(1)/3(1) on the N21-N23 molecular (Q(y)) axis is not necessarily important for the self-aggregation. The (1)H NMR and CD spectroscopic studies showed that the 674 nm absorbing species of 1R was characterized as a face-to-face "closed" dimer, while the 708 nm absorbing species of 1S was a large oligomer constructed with aggregation of head-to-tail "open" dimers. This diastereomeric control over the aggregation of 1R and 1S is more pronounced than that observed in the regioisomerically 3(1)-secondary alcoholic R/S-diastereomers 3R and 3S. The difference is ascribable to the conformational fixation of the 13(1)-hydroxyl group of the exo five-membered ring in 1. In contrast to self-aggregative 3(1)-tertiary alcoholic 4, both 13(1)-epimers of 13(1)-tertiary alcoholic 2 were monomeric even in nonpolar organic media: the additional 13(1)-methyl group (1 --> 2) drastically suppressed the self-aggregation due to the interference of the methyl group in intermolecular pi-pi interaction.     

Calculations find that tunneling plays a major role in the reductive elimination of methane from hydridomethylbis(trimethylphosphine)platinum: how to confirm this computational prediction experimentally

DFT calculations, including the effects of small curvature tunneling, have been performed on the reductive elimination of methane from hydridomethylbis(trimethylphosphine)platinum (1d). The calculations find that at 250 K tunneling results in an increase in the rate constant for reductive elimination by a factor of 4, a lowering of Ea by 1.7 kcal/mol, and a decrease in A by a factor of nearly 10. Tunneling is also calculated to increase the primary H/D kinetic isotope effect (KIE) from k(1d)/k(1f) = 2.26 to k(1d)/k(1f) = 4.12 and to result in a large secondary KIE of k(1d)/k(1e) = 1.35. In addition, tunneling is predicted to result in a violation of the rule of the geometric mean, so that the secondary KIE for reductive elimination of methane-d1 from 1f is calculated to be k(1f)/k(1g) = 1.06, which is much smaller than the secondary KIE of k(1d)/k(1e) = 1.35 for reductive elimination of methane from 1d. Comparison of the measured values of k(1d)/k(1e) and k(1f)/k(1g) is therefore proposed as an experimental test of the prediction that tunneling plays an important role in the reductive elimination of methane from 1d.     

Synthesis and characterization of an anomeric sulfur analogue of CMP-sialic acid

alpha-2,3-Sialyltransferase catalyzes the transfer of sialic acid from CMP-sialic acid (1) to a lactose acceptor. An analogue of 1 was synthesized in which the anomeric oxygen atom was replaced with a sulfur atom (1S). The key step in the synthesis of 1S was a tetrazole-promoted coupling of a cytidine-5'-phosphoramidite with a glycosyl thiol of a protected sialic acid. Compounds 1 and 1S were characterized for their activity in a sialyl transfer assay. The rate of solvolysis in aqueous buffer of analogue 1S was 50-fold slower than that of 1. Analogue 1S was found to be substrate for alpha-2,3-sialyltransferase. The K(m) of 1S was just 3-fold higher than that of 1, while the k(cat) of 1S was 2 orders of magnitude lower compared to 1.     

Sensing cytochrome P450 1A1 activity by a resorufin-based isoform-specific fluorescent probe

Cytochrome P450 1A1 (CYP1A1), a heme-containing monooxygenase, is of particular importance for human health because of its vital roles in the metabolic activation of pro-carcinogenic compounds to the carcinogens. Deciphering the relevance of CYP1A1 to human diseases and screening of CYP1A1 modulators require reliable tool(s) for probing this key enzyme in complex biological matrices. Herein, a practical and ultrasensitive fluorescence-based assay for real-time sensing CYP1A1 activities in biological systems has been developed, via designing an isoform-specific fluorogenic sensor for CYP1A1 (CHPO). The newly developed fluorogenic substrate for CYP1A1 has been carefully investigated in terms of specificity, sensitivity, precision, quantitative linear range and the anti-interference ability. The excellent selectivity, strong anti-interference ability and fast response kinetics, making the practicability of CHPO-based CYP1A1 activity assay is better than that of most reported CYP1A1 activity assays. Furthermore, CHPO has been successfully used for imaging CYP1A1 activities in living cells and human tissues, as well as for high-throughput screening of CYP1A1 inhibitors using tissue preparations as enzyme sources. Collectively, this study provided a practical fluorogenic sensor for real-time sensing CYP1A1 in complex biological systems, which would strongly facilitate the investigations on the relevance of CYP1A1 to human diseases and promote high-throughput screening of CYP1A1 modulators for biomedical applications.     

Phosphorus-Containing Dendrimers. Easy Access to New Multi-Difunctionalized Macromolecules

Phosphorus-containing dendrimers 1-[G'(1)]-1-[G'(4)] (generation 1 to generation 4) possessing terminal aldehyde groups reacted with a variety of hydrazino compounds. Addition of hydrazine itself to 1-[G'(1)]-1-[G'(4)] afforded the corresponding dendrimers 2-[G(1)]-2-[G(4)] with hydrazono groups at the periphery. Addition of methylhydrazine to 1-[G'(1)], 1-[G'(4)] gave the dendrimers 3-[G(1)], 3-[G(4)]. A Schiff reaction between 1-[G'(1)]-1-[G'(4)] and 1-amino-4-(2-hydroxyethyl)piperazine led to dendrimers 5-[G(1)]-5-[G(4)] possessing up to 48 alcohol chain ends. Treatment of 1-[G'(1)], 1-[G'(3)] with fluorenone hydrazone gave rise to macromolecules 7-[G(1)], 7-[G(3)] while the reaction of 1-[G'(1)], 1-[G'(2)], 1-[G'(4)] with 4-aminobenzo-15-crown-5 afforded the macromolecules 9-[G(1)], 9-[G(2)], 9-[G(4)] in which up to 48 crown ether units are anchored on the surface. Wittig reactions between 1-[G'(1)]-1-[G'(4)] with (acetylmethylene)triphenylphosphorane (10) or (cyanomethylene)triphenylphosphorane (12) allowed the formation of dendrimers 11-[G(1)]-11-[G(4)] or 13-[G(1)], 13-[G(4)] with alpha,beta unsaturated ketones or cinnamonitrile units, respectively, on the surface. Disubstitution of terminal P(S)Cl(2) groups of dendrimers 1-[G(1)]-1-[G(7)] with allylamine, propargylamine, or N-(trimethylsilyl)imidazole easily occurred to give macromolecules 14-[G(1)]-14-[G(7)], 15-[G(1)], 15-[G(4)], 16-[G(1)], 16-[G(4)].