Well-Defined and Highly Effective Nickel Catalysts Coordinated on Tridentate SNO Schiff-Base Derivatives for Alternating Copolymerization of Epoxides and Anhydrides.

A series of Ni complexes supported by SNO Schiff-base derivatives were synthesized in this study. Complex synthesis and characterization data are reported herein. Treatment of the pro-ligands [L1-H = 2-(((2-(methylthio)ethyl)imino)methyl)phenol, L2-H = 2,4-di-tert-butyl-6-(((2-(methylthio)ethyl)imino)methyl)phenol, L3-H = 2-(((2-(methylthio)ethyl)imino)methyl)-4,6-bis(2-phenylpropan-2-yl)phenol, L4-H = 4-bromo-2-(((2-(methylthio)ethyl)imino)methyl)phenol, and L5-H = 4-chloro-2-(((2-(methylthio)ethyl)imino)methyl)phenol] with Ni(OAc)2·4H2O in refluxing ethanol afforded six-coordinate mono-Ni(II) complexes [L2nNi] (n = 1-5). Noteworthy, a heptanuclear nickel(II) octacarboxylate species complex 6 and dinuclear nickel complex 6a resulted from treatment of L6-H [4-fluoro-2-(((2-(methylthio)ethyl)imino)methyl)phenol] with different metal precursors [Ni(OAc)2·4H2O for 6; NiBr2 for 6a] giving a quantitative yield. The reaction of nickel acetate tetrahydrate and L7-H to L9-H [L7-H = 2-methoxy-6-(((2-(methylthio)ethyl)imino)methyl)phenol, L8-H = 5-methoxy-2-(((2-(methylthio)ethyl)imino)methyl)phenol, and L9-H = 4-methoxy-2-(((2-(methylthio)ethyl)imino)methyl)phenol] produced the four-coordinate complexes [L2nNi] (n = 7-9). The highest performing catalyst was complex 3, which was highly efficient for the ring-opening copolymerization of phthalic anhydride (PA) and cyclohexene oxide (CHO) in the presence of a cocatalyst (4-dimethylaminopyridine). In addition, the same copolymerization conditions produced narrowly dispersed polyesters, with high selectivity and polymerization control. In addition to PA-CHO copolymerization, efficient diglycolic anhydride-PA and PA-propene oxide copolymerization was achieved under the same conditions. These catalysts are straightforward to produce and extend the scope of potential substrates.

Photocytotoxic Copper(II) Complexes with Schiff-Base Scaffolds for Photodynamic Therapy.

Photodynamic therapy (PDT) is a promising and minimally invasive method for the treatment of superficial diseases, and photosensitizers with high phototoxicity indices (defined as (IC50dark )/(IC50irradiation )) are essential for the development of ideal photosensitizing properties for this technology. Herein, we report a series of photocytotoxic copper(II) complexes [Cu(R QYMP)(dppn)] (R QYMP=N,N,O-tridentate Schiff-base derivatives, dppn=benzo[i]dipyrido[3,2-a;2',3'-c]phenazine), the structures of which have been confirmed by mass spectrometry and FTIR spectroscopy. X-ray crystallography revealed that the CuN4 O core of the [Cu(cumyl QYMP)(dppn)](ClO4 ) complex (3) has a distorted square-pyramidal geometry. Phototoxicity indices of 329 against human squamous cell carcinoma (SCC15) and 296 against basal cell carcinoma (BCC) cell lines have been determined with [Cu(3-OMe QYMP)(dppn)](ClO4 ) (4). This can be attributed to the formation of reactive oxygen species, cell apoptosis, and caspase-3 activation, indicating high potential of complex 4 as a photosensitizer candidate in PDT. Thus, copper complexes bearing suitable Schiff-base ligands with a dppn co-ligand may be considered for the design of efficient metal-based anticancer agents for PDT.

Interpenetrating Metal-Metalloporphyrin Framework for Selective CO2 Uptake and Chemical Transformation of CO2.

Herein we report a robust primitive cubic (pcu)-topology metal-metalloporphyrin framework (MMPF), MMPF-18, which was constructed from a ubiquitous secondary building unit of a tetranuclear zinc cluster, Zn4(µ4-O)(-COO)6, and a linear organic linker of 5,15-bis(4-carboxyphenyl)porphyrin (H2bcpp). The strong π-π stacking from porphyrins and the lengthy H2bcpp ligand affords a 4-fold-interpenetrating network along with reduced void spaces and confined narrow channels. Thereby, MMPF-18 presents segmented pores and high-density metalloporphyrin centers for selective CO2 uptake over CH4 and size-selective chemical transformation of CO2 with epoxides forming cyclic carbonates under ambient conditions.

Synthesis of Sodium Complexes Supported with NNO-Tridentate Schiff Base Ligands and Their Applications in the Ring-Opening Polymerization of L-Lactide.

A series of sodium complexes bearing NNO-tridentate Schiff base ligands with an N-pendant arm were synthesized and used as catalysts for the ring-opening polymerization of L-lactide (L-LA). Electronic effects of ancillary ligands coordinated by sodium complexes substantially influence the catalysis, and ligands with electron-donating groups increase the catalytic activity of the sodium complexes for catalyzing L-LA polymerization. In particular, a sodium complex bearing a 4-methoxy group has the highest activity with conversion up to 95% within 30 s at 0 °C and a low polydispersity index of 1.13, whereas the 4-bromo group showed the poorest performance with regard to the catalytic rate of L-LA polymerization in the presence of benzyl alcohol (BnOH). (1)H NMR pulsed-gradient spin-echo diffusion experiments and single-crystal X-ray analyses showed that sodium complexes [L(H)Na(THF)]2 and [L(4-Cl)Na(THF)]2 were dinuclear species in both solution and the solid state. The kinetic results indicated a first-order dependence on each of [[L(4-Cl)Na]2], [l-LA], and [BnOH].

Dinuclear and Trinuclear Nickel Complexes as Effective Catalysts for Alternating Copolymerization on Carbon Dioxide and Cyclohexene Oxide.

A series of novel nickel complexes 1-9 supported by NNO-tridentate Schiff-base derivatives have been synthesized and characterized. Treatment of the pro-ligands [L(1)-H = 2,4-di-tert-butyl-6-(((2-(dimethylamino)ethyl)imino)methyl)phenol, L(2)-H = 2-(((2-(dimethylamino)ethyl)imino)methyl)-4,6-bis(2-phenylpropan-2-yl)phenol, L(3)-H = 2-(((2-(dimethylamino)ethyl)imino)methyl)phenol] with Ni(OAc)2·4H2O in refluxing ethanol afforded mono- or bimetallic nickel complexes {[(L(1))Ni(OAc)] (1); (L(2))Ni(OAc)] (2); (L(3))2Ni2(OAc)2(H2O)] (3)}. Alcohol-solvated trimetallic nickel acetate complexes {[(L(3))2Ni3(OAc)4(MeOH)2] (4); (L(3))2Ni3(OAc)4(EtOH)2] (5)} could be generated from the reaction of L(3)-H and anhydrous nickel(II) acetate with a ratio of 2:3 in refluxing anhydrous MeOH or EtOH. The reaction of nickel acetate tetrahydrate and L(4)-H to L(6)-H [L(4)-H = 2-(((2-(dimethylamino)ethyl)imino)methyl)-5-methoxyphenol, L(5)-H = 2-(((2-(dimethylamino)ethyl)imino)methyl)-4-methoxy-phenol, L(6)-H = 2-(((2-(dimethylamino)ethyl)imino)(phenyl)methyl)phenol] produced, respectively, the alcohol-free trinuclear nickel complexes {[(L(4))2Ni3(OAc)4] (7); [(L(5))2Ni3(OAc)4] (8); [(L(6))2Ni3(OAc)4] (9)} with the same ratio in refluxing EtOH under the atmospheric environment. Interestingly, recrystallization of [(L(3))2Ni3(OAc)4(MeOH)] (4) or [(L(3))2Ni3(OAc)4(EtOH)] (5) in the mixed solvent of CH2Cl2/hexane gives [(L(3))2Ni3(OAc)4] (6), which is isostructural with analogues 7-9. All bi- and trimetallic nickel complexes exhibit efficient activity and good selectivity for copolymerization of CO2 with cyclohexene oxide, resulting in copolymers with a high alternating microstructure possessing ≥99% carbonate-linkage content. This is the first example to apply well-defined trinuclear nickel complexes as efficient catalysts for the production of perfectly alternating poly(cyclohexene carbonate).

Structurally diverse copper complexes bearing NNO-tridentate Schiff-base derivatives as efficient catalysts for copolymerization of carbon dioxide and cyclohexene oxide.

Structurally diverse copper acetate complexes based on NNO-tridentate Schiff-base ligands were synthesized and characterized as mono-, di-, and trinuclear complexes with respect to varied ancillary ligands. Treatment of the ligand precursors (L(1)-H = 2-(1-((2-(dimethylamino)ethyl)imino)ethyl)-4-methylphenol, L(2)-H = 4-chloro-2-(1-((2-(dimethylamino)ethyl)imino)ethyl)phenol, and L(3)-H = 2-(1-((2-(dimethylamino)ethyl)imino)ethyl)-5-methylphenol) with Cu(OAc)2·H2O (1 equiv) in refluxing ethanol afforded five-coordinate mono- or bimetallic copper complexes ([(L(1))Cu(OAc)(H2O)] (1); [(L(2))Cu(OAc)(H2O)] (2); [(L(3))2Cu2(OAc)2] (3)) in high yields. Dinuclear copper acetate analogue [(L(1))2Cu2(OAc)2] (4) resulted from treatment of L(1)-H as the ligand precursor in refluxing anhydrous MeOH with equimolar proportions of metal acetate salt under a dry nitrogen atmosphere. However, a trinuclear complex, [(L(4))2Cu3(OAc)4] (5), was obtained on utilizing 2-(1-((2-(dimethylamino)ethyl)imino)ethyl)-5-methoxyphenol (L(4)-H) as the proligand under the same synthetic route of 1-3; this complex was also synthesized in the reaction of L(4)-H and copper(II) acetate monohydrate in the ratio of 2:3, giving a quantitative yield. All complexes are active catalysts for copolymerization of cyclohexene oxide (CHO) and CO2 without cocatalysts. In particular, dinuclear Cu complex 3 performed satisfactorily to produce polycarbonates with controllable molecular weights and high carbonate linkages. These copper complexes are the first examples that are effective for both CO2/CHO copolymerization and formation of polymers in a controlled fashion.

Tetracosanuclear nickel complexes as effective catalysts for cycloaddition of carbon dioxide with epoxides.

A series of well-defined tetracosanuclear nickel complexes 3-7 facilely produced by one-pot synthesis were active catalysts for cycloaddition of CO2 and cyclohexene oxide (CHO). These nickel complexes were doughnut-like supramolecular coordination complexes involving eight repeating units, and each of them contains one Schiff base ligand and three nickel(II) ions. Notably, the 24-nuclear nickel cluster complex 3 in combination with nucleophilic additives was the most efficient catalyst to mediate CO2 coupling with CHO to generate CO2-based cis-cyclohexene carbonates. In addition to CO2/CHO cycloaddition, complex 3 was also found to effectively couple CO2 with other alicyclic epoxides, generating the corresponding cyclic carbonates. Additionally, kinetic investigations for CO2 cycloaddition of CHO using 3 were reported.

Effective topical treatments using innovative NNO-tridentate vanadium(IV) complexes-mediated photodynamic therapy in a psoriasis-like mouse model.

Psoriasis is a chronic inflammatory skin disease that can significantly impact the quality of human life. Various drug treatments are available; however, due to their long-term severe side effects the usage of these drugs is limited. Photodynamic therapy (PDT) has been clinically approved for skin diseases due to its non-invasive nature. We present novel NNO-tridentate vanadium(IV) complexes used in PDT for anti-inflammatory effects in an imiquimod-induced psoriasis-like skin disease mouse model. The vanadium(IV) complexes (1-4) were synthesized using the NNO-tridentate ligand with a benzo[i]dipyrido[3,2-a;2',3'-c]phenazine (dppn) moiety, and were characterized by UV/Visible spectroscopy, EPR spectroscopy, NMR (1H, and 13C) spectroscopy, electrospray ionization mass (ESI-MS) spectrometry and cyclic voltammetry (CV) studies. The photocytotoxicity of vanadium(IV) complexes (1-4) was low under dark conditions and complex (4) showed remarkable photocytotoxicity under blue light (430 nm, 8 W cm-2, 30 min) irradiation. Moreover, [VO(t-butylL)(dppn)] (4)-mediated PDT down-regulated inflammatory cytokines IL-17A and IL-22 in the psoriasis-like mouse model, which could evidence the significant relieving of the psoriatic-like symptoms in the mouse model. Overall, these results suggested that [VO(t-butylL)(dppn)] (4) could be a potential candidate for the treatment of psoriasis both in vitro and in vivo.

Ring-opening polymerization by lithium catalysts: an overview.

This critical review summarizes recent developments in the preparation and application of lithium catalysts/initiators such as, alkyl lithium, alkoxy lithium and bimetallic lithium compounds for ring-opening polymerization (ROP). The ROP of cyclic esters, cyclic carbonates, cyclo-silazanes, cyclo-silanes, cyclo-siloxanes, cyclo-carboxylate, cyclic phosphirene and quinodimethanes are covered in this review. The present paper emphasizes the polymerization kinetics and the control exhibited by the different types of lithium initiators/catalysts. For the cases where useful properties, such as high molecular weight, narrow PDI, or stereocontrol, have been observed, a more detailed examination of the mechanistic studies of the catalysts/initiators are provided. Furthermore, this review also focuses on the synthesis of block copolymers and graft copolymers by ROP principle. The topics covered in this review regarding lithium compounds toward ROP will be of interest to inorganic, organic and organometallic chemists, material, polymer and catalytic scientists due to its unique mode of activation as compared to transition and inner transition-metals. In addition, use of these compounds in catalysis is steadily growing, because of the complementary reactivity toward ROP as compared to other metals. Finally, some aspects and opportunities which may be of interest in the future are suggested (143 references).

Bulky bisphenol ligand-supported aluminum-sodium inverse crown ether complex.

A mixed aluminum-sodium phenolate ring compound with an oxo core has been synthesized and crystallographically characterized as a new inverse crown ether complex, together with some of its precursors. The experimental results showed that the Al-Na inverse crown ether can be obtained from two different approaches: (1) hydrolysis of [(EDBP)Al(CH(3))(2)Na(THF)(2)] (1), followed by condensation with [(EDBP)Al(CH(3))(mu(2)-OH)Na(THF)(3)] (2); (2) fast redox reaction by oxidation of a methyl group on complex 1 and reduction of molecular oxygen to oxide.

Synthesis and structural studies of heterobimetallic alkoxide complexes supported by bis(phenolate) ligands: efficient catalysts for ring-opening polymerization of L-lactide.

A series of heterobimetallic titanium(IV) complexes [LTi(O(i)Pr)(mu-O(i)Pr)(2)Li(THF)(2)], [LTi(O(i)Pr)(mu-O(i)Pr)(2)Na(THF)(2)], [LTi(mu-O(i)Pr)(2)Zn(O(i)Pr)(2)], and [LTi(mu-O(i)Pr)(2)Mg(O(i)Pr)(2)] (where L = bidentate bisphenol ligands) have been synthesized and characterized including a structural determination of [L(1)Ti(mu(2)-O(i)Pr)(2)(O(i)Pr)Li(THF)(2)] (1a). These complexes were investigated for their utility in the ring-opening polymerization (ROP) of l-lactide (LA). Polymerization activities have been shown to correlate with the electronic properties of the substituent within the bisphenol ligand. In contrast to monometallic titanium initiator 1e, all the heterobimetallic titanium initiators (Ti-Li, Ti-Na, Ti-Zn, and Ti-Mg) show enhanced catalytic activity toward ring-opening polymerization (ROP) of l-LA. In addition, the use of electron-donating methoxy or methylphenylsulfonyl functional ligands reveals the highest activity. The bisphenol bimetallic complexes give rise to controlled ring-opening polymerization, as shown by the linear relationship between the percentage conversion and the number-average molecular weight. The polymerization kinetics using 2c as an initiator were also studied, and the experimental results indicate that the reaction rate is first-order with respect to both monomer and catalyst concentration with a polymerization rate constant, k = 81.64 M(-1) min(-1).

Synthesis and structural studies of lithium and sodium complexes with OOO-tridentate bis(phenolate) ligands: effective catalysts for the ring-opening polymerization of L-lactide.

A series of lithium and sodium complexes with OOO-tridentate bis(phenolate) ligands have been synthesized and fully characterized. The reaction of 2,2'-dihydroxy-3,3',5,5'-tetrakis[(1-methyl-1-phenyl)ethyl]dibenzyl ether (L(1)-H(2)) with different ratios of (n)BuLi in toluene or tetrahydrofuran (THF) gave [Li(2)(L(1)-H)(2)] (1), [Li(4)L(1)(2)] (2), and [Li(2)L(1)(THF)(3)] (3), respectively. Similarly, [Na(L(1)-H)(THF)] (4), [Na(2)(L(1)-H)](2) (5), and [Na(4)L(1)(2)] (6) were prepared by the reaction of L(1)-H(2) and NaN[Si(CH(3))(3)](2) or sodium metal. In addition, the reaction of 2,2'-dihydroxy-3,3',5,5'-tetra-tert-butyldibenzyl ether (L(2)-H(2)) with (n)BuLi in toluene or THF yields Li(2)(L(2)-H)(2)] (7) and [Li(2)(L(2)-H)(2)(THF)(2)] (8), respectively. Further treatment of 7 with 2 mol equiv of benzyl alcohol provides [Li(2)(L(2)-H)(2)(BnOH)(2)] (9). Complexes 1-4 and 6-9 have been structurally characterized by single-crystal X-ray analysis. The dinuclear nature of complexes 1 and 3 was confirmed from their molecular structure. Complexes 2 and 6 illustrate tetranuclear species; however, complex 4 shows a mononuclear feature. A p-π interaction exists from the phenyl ring of the 2-(methyl-1-phenylethyl) groups to the central metal in complexes 2, 4, and 6, which could effectively stabilize the metal center. Among them, complexes 1, 2, and 5-9 displayed efficient catalytic behavior for the ring-opening polymerization of L-lactide in the presence of benzyl alcohol. Experimental results indicate that among these alkali-metal complexes, the sodium compound 6 displays a rapid catalytic polymerization of L-lactide in "living" fashion, yielding poly(L-lactide) with a controlled molecular weight and narrow polydispersity indices for a wide range of monomer-to-initiator ratios.

Preparation, characterization, and catalytic studies of magnesium complexes supported by NNO-tridentate Schiff-base ligands.

A series of magnesium benzyl alkoxides, [LMg(mu-OBn)](2) (1-8), supported by NNO-tridentate Schiff-base ligands are prepared by the reactions of Mg(OBn)(2) with one molar equivalent of related Schiff-base ligands (L(1)H-L(8)H) in toluene. The molecular structures of compounds 2, 3, 7, and 8 are characterized by X-ray structure determination. All of these compounds are crystallized as penta-coordinated dimers, and the central magnesium atoms are bridged by the oxygen atoms of benzyl alkoxides. The catalytic activities of complexes 1-8 toward the ring-opening polymerization of l-lactide are investigated. Experimental results indicate that the reactivity of [LMg(mu-OBn)](2) (1-8) is dramatically affected by the electronic effect of the substituents on the Schiff-base ligands, and 4 has the highest activity among them.

Bis(µ-phenyl-methano-lato)bis-({4-[(E)-(4-tert-butyl-phen-yl)(2-pyrid-ylmethyl-imino)meth-yl]-3-methyl-1-phenyl-1H-pyrazol-5-olato}zinc(II)).

In the title centrosymmetric dimeric Zn(II) complex, [Zn(2)(C(27)H(27)N(4)O)(2)(C(7)H(7)O)(2)], the Zn(II) center is coordinated by two N atoms and one O atom of the ketiminate ligand and two bridging O atoms of the benzyl-alkoxy groups. The geometry around the Zn(II) ions is distorted trigonal-bipyramidal.

(2,2'-Bipyridine)(2-{1-[2-(dimethyl-amino)ethyl-imino]eth-yl}-4-methoxy-phenolato)copper(II) perchlorate.

The Cu atom of the title complex, [Cu(C(13)H(19)N(2)O(2))(C(10)H(8)N(2))]ClO(4), has a distorted square-pyramidal geometry with all three of the donor atoms from the N,N',O-tridentate Schiff base ligand in the equatorial positions and the bipyridine N atoms in an equatorial-axial binding mode. The Cu atom is 0.1801 (11) Šabove the N(3)O mean basal plane.

Synthesis and Characterization of N,N,O-Tridentate Aminophenolate Zinc Complexes and Their Catalysis in the Ring-Opening Polymerization of Lactides.

A series of aminophenolate ligands with various pendant groups and associated ethyl Zn complexes were synthesized and studied as catalysts for the ring-opening polymerization (ROP) of lactides (LAs). The thiophenylmethyl group (L 4 ZnEt) increased the catalytic activity more than the benzyl group (L 1 ZnEt) did, and 2-fluorobenzyl (L 3 ZnEt) and 2-methoxybenzyl (L 2 ZnEt) groups had the opposite effect. In addition, the LA polymerization mechanism proved by Nuclear Magnetic Resonance and Density Function Theory was that LA was attracted by H···O bond of an α-hydrogen of the LA molecule and the phenoxyl oxygen of the catalyst. After the dissociation of amino group from the Zn atom, the benzyl alcohol initiated LA without replacing the ethyl group of Zn complex. It is the first case where the ethyl group is regarded as a ligand and cannot be replaced by benzyl alcohol, and this information is very important for the mechanism study of ROP.

Mono- and dinuclear copper complexes coordinated on NNO-tridentate Schiff-base derivatives for copolymerization of cyclohexene oxide and cyclic anhydrides.

A series of bimetallic penta-coordinated copper complexes [Ln2Cu2(OAc)2] (1, 3-7), a mononuclear tetra-coordinated copper complex [LnCu(OAc)] (8 and 9), and a penta-coordinated copper complex [L2Cu(OAc)(H2O)] (10) were prepared by the reaction of Cu(OAc)2·H2O with a variety of NNO-tridentate Schiff-base ligands (L1-H-L9-H) in refluxing 95% ethanol, respectively. However, a dinuclear copper complex [(L2)2Cu2(OAc)2] (2) can be obtained from the treatment of L2-H with a stoichiometric amount of anhydrous Cu(OAc)2 in refluxing absolute EtOH under a dry nitrogen atmosphere. All of these copper complexes are active for the alternating copolymerization of cyclohexene oxide and cyclic anhydride, affording polyesters with moderate polydispersity. In particular, dinuclear copper complexes 1 and 2 performed satisfactorily to produce polyesters with controllable molecular weights and high ester linkages. This is the first example of well-defined copper acetate catalysts active for the copolymerization of cyclohexene oxide-phthalic anhydride or cyclohexene oxide-succinic anhydride which may be advantageous in terms of obviating the use of co-catalysts and low cost as well as an effective copolymerization for the formation of biodegradable polyesters in a controlled fashion.

Cell migration rate on poly(epsilon-caprolactone)/poly(ethylene glycol) diblock copolymers and correlation with the material sliding angle.

The nanostructure of a biomaterial surface has strong influence on cell behavior. The migration of cells on nanostructured surfaces, however, has not been investigated so far. In this study, we used PCL/PEG diblock copolymers as model surfaces to examine the effect of nanoislands on migration of different cells, including fibroblasts and endothelial cells. The water sliding angle of the substrates was measured. The cell migration rate was examined under a real-time optical microscope. It was found that a greater cell migration rate correlated with the smaller sliding angle of the substrate.

(µ-4-Bromo-2-{1-[2-(dimethyl-amino)ethyl-imino]eth-yl}phenolato)bis-[ethyl-zinc(II)].

The title complex, [Zn(2)(C(2)H(5))(2)(C(12)H(16)BrN(2)O)(2)], is dimeric, bridged through the O atoms of the phenolate anions. The molecule lies on a crystallographic twofold rotation axis. Each Zn atom is penta-coordinated by two N atoms and two bridging O atoms of the tridentate salicylideneiminate ligands and one C atom from an ethyl group, forming a distorted square-pyramidal environment.

Mono-, di- and tetra-zinc complexes derived from an amino-benzotriazole phenolate ligand containing a bulkier N-alkyl pendant arm: synthesis, structure and catalysis for ring-opening polymerization of cyclic esters.

Zinc complexes constructed from the amino-modified benzotriazole phenol pro-ligand, 2-(2H-benzotriazol-2-yl)-6-((diisopropylamino)methyl)-4-(2,4,4-trimethylpentan-2-yl)phenol ((C8DIA)BTP-H, 1), were synthesized stepwise and structurally characterized. The reaction of (C8DIA)BTP-H (1) with one equivalent of diethyl zinc (ZnEt2) generates a dimeric and four-coordinated zinc complex, [(µ-(C8DIA)BTP)ZnEt]2 (2), which is doubly bridged by two phenolate groups of C8DIABTP ligands. Further reaction of 2 with benzyl alcohol (BnOH) in stoichiometric proportions affords a tetranuclear zinc benzylalkoxide complex [(µ-OBn)((C8DIA)BTP)Zn]4 (3) that possesses a saddle-shaped core with four µ2-bridging benzylalkoxy groups upon four Zn centres. Interestingly, the di-nuclear Zn alkoxide [(µ-OBn)((C8DIA)BTP)Zn(DMAP)]2 (4) could be prepared by treatment of 3 with a stoichiometric amount of 4-(dimethylamino)pyridine (DMAP). ZnEt2 reacts with two equivalents of 1 in the presence of DMAP (1.0 mol equiv.) to yield a five-coordinated mononuclear zinc complex, [((C8DIA)BTP)2Zn(DMAP)] (5). All complexes adopt an N,O-bidentate coordination mode from the phenoxy oxygen atom and benzotriazole nitrogen atom, in which the nitrogen atom of the pendent arm substituent is not coordinated to the zinc centre. Ring-opening polymerization of ε-caprolactone and ß-butyrolactone catalysed by 2 and 3 was investigated.